If you don't know anything about blogging   please post your question here.
I will try my best to teach you how:
1. search for a keywords (Ill prefer micro niche since its easy to rank in Google - just in 3 months or less)
2. optimized a site (on site seo )
3. off site optimization (back links)
4. if you don't have a hosting  ( you can buy it from me it you want ) but no need for you to buy if you don't have extra money, you can used blogger or WordPress  but i prefer that you should have your own domain and hosting.. 
and much more .. 
So what are you waiting for lets do some blogging to earn money
lets  try to make this thread helpful for all the newbies out there.. (no need to spend money if you don't want  to)
and for those who have experience (experts) with  IM , SEO and Blogging feel free to post your experience and share here..  Lets help the noobs to earn money
peace
Most Expanded Explanation to Find  the niche  of your choice s. Note: Am not the original author of the article below  but I feel like i want to post it here  because many of you do not know how to search for niche.
To begin with, I check out the hottest search trends at Google's 
Hot Trends. At this point I am just looking for ideas.
If I see that a particular topic is hot, I’ll make a note of it and look  at more targeted sub-niches later on at more specialized sites (which  I’ll show you in just a minute!).
The 
Lycos Top 50 is  another site, like Google's Hot Trends, where I will review the latest  trends and look for hot topics to explore further. I will also look at 
Yahoo! Buzz for ideas as well.
The 
eBay Pulse site  is a great place to start looking at sub-niches. What I will do is  select the category first (using the topics I’ve gathered from looking  at the previous sites), then look for profitable sub-niches by then  selecting a sub-category.
The best chance for success is if I am as specific as possible with my  niche selection. In the example below, I don’t want to sell to the  “crafts” niche.
I want to sell to grandmothers who enjoy giving their latch rug hooking  gifts to their families and friends. Whatever. You get the idea.
Also, I’ll always check the largest stores as well to see what they’re  selling. There has to be a reason they are the largest stores. They must  be doing something right.
TIP: eBay also puts out a PDF report of their hottest categories each month, available at 
http://pages.ebay.com/sellercentral/hotitems.pdf.
Now that I have some potential sub-niches to work with, I want to see how much of a market there is there.
Just because a sub-niche is popular doesn’t mean people spend money on it.
Amazon is a great place to see what currently exists for any given sub-niche.
Chances are, the more books there are written on that subject, the more that market spends on those topics.
For example:
First I specify “Books” to search. Then I enter my niche, in this case “crafts.”
Uh oh. There are WAY too many books returned. This niche is not targeted enough. It is too “mainstream.”
Much better! There are possibilities here.
We now suspect the following:
1) This sub-niche may be targeted enough.
2) This sub-niche may spend money.
Once you have an idea of which niche you want to target, it’s time to  determine its profitability. For this, you would have to use the tools  found at:
http://freekeywords.wordtracker.com/
Or…
http://www.digitalpoint.com/tools/suggestion/
Simply type in the idea you have in mind, and press the submit button.  You will then be presented with a list of keywords and key phrases that  are related to the subject you have entered. Each keyword or key phrase  would have an indication of the number of searches that they have  gathered from search engine users. The number of searches made for a  particular keyword or key phrase is a good barometer of the demand.  You’d want at least 5,000 searches for your main keyword.
Here are several other sites you can use to get niche ideas:
Nichebot - 
http://www.nichebot.com
Shopping.com Top Searches – 
Popular Pages on Shopping.com
AOL Hot Searches - 
Top search topics, trends & stories around the web - Aol Hot Searches
Google Groups - 
http://groups.google.com
Craig's List - 
craigslist: dallas / fort worth jobs, apartments, personals, for sale, services, community, and events
Delicious Popular - 
http://del.icio.us/popular
Dig - 
Digg - What the Internet is talking about right now
Google Catalogs - 
Google
Google Suggest – 
Google
Technorati - 
Technorati
Also, I'll do several targeted searches in both Google and Yahoo (for example, on the subject of "hobbies").
And of course I will always Google my keywords and check out the  competition in the Adwords ads. In this case I pay special attention to  the ads that sell information products (or services like mine if I’m  selling a service).
Some of the ads will be irrelevant as far as competition goes.
Ok, the next thing I'll do is check how many magazines there are on the subject of my chosen niche.
Ok, the next thing I'll do is check how many magazines there are on the subject of my chosen niche.
There are two places I go online for that:
Magazines.com - 
Magazine Subscription Discounts & Deals | Magazines.com
and
Amazon – 
Amazon.com: Magazine Subscriptions
At each site, I search by category to find the magazines in my niche.
Obviously the more the better, up to a point.
For example, golf has a lot of magazines, but it's not a good niche by  itself. It needs to be more targeted. But in that case I can always get  more targeted sub-niche ideas within that topic by looking at the types  of magazines for that topic.
The next thing to do to find out more about a niche is to visit the  forums. By visiting forums and taking note of what people are most  concerned about you can search the Internet for products and services  that will help them solve those problems. Gather the information about  the topic. Do some spy work.
Continuation
Understanding Your Target Audience
Ok, now that we have a niche, it’s time to figure out the psychographics of your target market.
According to Dictionary.com, psychographics means “the use of  demographics to determine the attitudes and tastes of a particular  segment of a population, as in marketing studies.”
In simpler terms, it means looking deeper into your niche market, so you can serve them better by customizing your products.
Answer a few questions… but I warn you not to answer them too quickly.  This takes a lot of thought and consideration to do correctly.
Question: Who would like to buy what you have to offer?
Don't just say ‘Women’. That is a gender identification, not a target  market. All women are not alike. They have a wide variety of lifestyles,  values and interests.
Don't just say ‘Golfers’. That identifies a group of people who partake  of a sporting activity but it’s not a target market. Among golfers there  are huge differences. Are you targeting the ever so often golfer with a  cheap tips video or are you targeting the lifestyle golfer who travels  regularly to play in competitions.
Be very specific. ‘Start up Fundraiser Coaching Professionals”
Question: Why is he/she interested in what you have to sell?
Don’t say ‘She will like it because she is a Mom’ because there are no  products that ‘all moms’ are interested in. (Unless it’s an Artificial  Intelligence Housekeeper and I think even then you’d get a few  naysayers.)
Be very specific. ‘Start up Fundraiser Coaching Professionals” will want  to secure this product because it contains the tricks and skill  builders they need to attract their first clients.’
Question: What stage of life is she in?
• Young & Single
• Young & Married
• Young Motherhood
• Middle Motherhood
• Late Motherhood
• Empty Nest
• Older & Single
• Older & Married
These stages of life are important factors in identifying a target  market. How you choose to communicate with your potential clients, you  will need to take this information into consideration.
What motivates a young married woman isn’t going to motivate an empty nester.
For example, if you want to reach young singles you’ll probably want to  use graphics and promotional materials that look trendy and highly  relative or popular to modern day media.
On the other hand, to reach older married people you will choose a more  traditional style and convey a stability that will resonate with older  consumers.
Question: How much money does he/she have to spend?
• Frugal
• Average
• Upper Middle Class
• Wealthy
Financial income brackets are one of the most important issues in choosing and communicating with your target market.
The financially strapped customer will be attracted to messages that imply that they’re getting a great value or saving money. 
Wealthy customers will be more interested in hearing that your product  is made of the best ingredients and created for distinctive tastes.
Some individuals will only be interested in products that clearly  demonstrate that they’re cheaper than everything else. They’re so driven  by their tight budget or their personal commitment to frugality that  they’ll choose one product over another on price point alone.