How to use and integrate Google api's

Steps to integrate gmail watch api in our app along with oauth2.0 help

You should search how to use rest apis

Could u please tell me what are put,post,get method s of web component and how to use them

Web component is used to communicate with servers using HTTP protocol. GET, POST, PUT are all different HTTP methods.

I request you to learn HTTP on Tutorials Point or any site you like.