go to blogger.com/wordpress.com and go through the steps to create a blog..

you can create blog by using blogger.com site and follows the step to create the blog and create a blog on the topic about which you know completely.

after creating the blog ...you have to add content to your blog consistently over a period of time....wiithout content your blog will not br recognized by anyone....

To create a blog:

Browse blogger.com
Login with a gmail id.
Then click on creat new blog
then title column will come
then give a title according to the concept you are going to blog then
url address column will appear then write a address according to the concept your going to blog.
then click continue.
there for the blog redirects to blog post.
and you can start blogging what every you want.

Try to blog for few days.
To get visitors its good to include an image related to blog concept in the post.As according to the visitors, visitors won't visit the pages without images.the content you put in the blog posts is better to keep own writen content. dont keep copied one.

After few days of blogging, apply your blog for adsense. google adsense is a ad marketing affiliate program. if they approve our blog we can display their ads in our blog. So that people who visit our blog they may click the ads. so that we get credited. These clicks should reach 100$ credit. then we will receive the check.

Most of the people are earning only on blogging. They made blogging as their full time job.

For example:
Amit chavla. He used to work as a software engineer and in home he used to do blogging. His blogging went well. He started earning in lakhs on blogging so he resigned his job and concentrated on blogging.

His blog is http://labnol.blogspot.com, http://labnol.com

Thank you sarala I had known how to create a blog.You are a very good person.

Nice explanation Saralaji.But I want to ask wheather creating blog is expensive or not?If yes what will be the cost.

creating blog is free of cost . You no need to spend any amount on it

Creating a blog is very easy and simple, but writing quality contents for the blog is a must if you want to earn some money from it. You have to attract people to your blog by advertising your blog in various blog directories, blog forums and write articles for various article sites. This recognises you as a good blog writer and thus as your name is advertised, more people will visit your blog and clicking on the adsense ads will surely bring you some revenue.

I just like to blog,but never tried to earn from it,even though a had adsense account.

blogging is an effective tool to earn money. but your blog should have enough page views per day id you want to earn anything worthwhile.if you want page views you need to add quality content in to your blogs to make people interesting