I haven't added my site in google webmaster but when I google search my site first 3 results belong to...?

[Jake]

First bear in mind that showing up in a search for your own name is one of the least valuable results, you need to rank for the topics of your site, not it's name, it's trivial to rank for a unique name no one else has on the web.

To see all pages that have been indexed, do a search for: site:yoursite.com (use no spaces)

Search engine spiders can 'discover' a site that has been linked to by following the links from sites already indexed. I don't bother to submit a site for indexed, instead I secure a few backlinks, which are needed to raise ranking anyway.

Realistically if you have a decent user navigation system not employing tricky scripts the search engines will find all of your pages, the enterprise sites with thousands of pages are the ones that must use a site map to get as much of their site indexed as possible.

Webmaster tools has other useful tracking and optimization services, you are also able to receive warning messages, like the recently pervasive "Unnatural link pattern" warning resulting from excessive SEO which can get a site de-indexed.

Learn about using the Google keyword research tool to find search phrases you would want to rank for by including them in some of your content.

https://adwords.google.com/select/KeywordToolExternal