Hi, i m new in search engine optimization... any one say me what is use of Google Web master tool, and how can i use this for my site.
Log in to the google webmaster, verified your site, and use the tools : )) You can check about keywords that people find you by, search queries Whether your site is indexed, and how many pages and whether to use www or non www and lots more tools. USE IT !
Yes Nystul telling you right. First need to login in webmaster tool and must your website verify by the Google. Even you can submit your website sitemap in Google thus your website is indexed by the Google easily.
You can verify your website through uploading a html page, or placing meta tag. still uploading an html page is good practice, imo.
You can find all information about google webmaster tools here google.com/webmasters/tools/docs/en/about.html
Google webmaster tools is very easy to use specially for the new SEO webmaster. Here you can get list your website and gets details how to go with website for search engines.
From my experience when you verify your newly created site in Google Webmaster Tools and submit it's sitemap it gets indexed very quickly. That's another use of GWT.