A Google webmaster tool is online software for webmaster optimizes their website to fit Google search engine. Actually, it is a good SEO optimization tools. All you need to do is to have a Google Account and claim your site and after Google verifies your ownership you get to use these features.

So, first step:
Go to https://www.google.com/webmasters/tools/
Log in as your Google account, then add your site below the Dashboard.
Click Add Site.

Next screen, here are two methods for verifying your site.
1- You can upload a page with name as suggested by Google (empty file).
2- You can add a Meta tag given by Google to your home page.
If you are unable to get your site by two methods above, then you need to check with your host. They may have made settings that sends a 200(OK) status even for pages that don’t exists for which either 404(unavailable but may appear) or 410(permanently removed) status.

After this step, you will see the dashboard page with a summary about your site:
You can see when the last time Google crawl your page is, and how about your website index status. Here is a shortcut which you can click to see the Top search queries.

But now, is it not useful for us now, because Noture has not any data in this stage. But here still are some things we need to do on Google Webmaster Tools.

If Google already crawled your site, you can go to
Click Dignostics => Web Crawl: to check is their any mistake on your site, if you had, you should fix them as soon as you can.

If Google did not crawl the site, we still can go to:
Click Sitemaps => Add sitemap: It will help Google easy find the links on your site. You can submit by TXT or XML.

Click Tools => Set geographic target: as Google said: If your site is aimed at users in a particular location, you can associate your site with a geographic target. We’ll use this information to help us determine how your site appears in location-specific search results.
Simply tick Associate a geographic location with this site, then select the country which you want.

Done.

In the future, when the website growing, we can use another tools on Google Webmaster Tools.

Diagnostics: To check the error on website
Statistics: Know your website statistics
Tools:
Set crawl rate: Set how often Google crawl your site.
Remove URLs: Remove unused URL from search engine database

Hope this artistes help for the new guys use Google Webmaster Tools.