As I told you in your other thread, you simply sign up for a webmaster account and follow the instructions to add a site. Log in to your account and you will see the "Add a site" button. You will know it's been added because it will appear in your list of sites in your account.
Sorry, but there are two many basic questions there. It is not the purpose of a forum to teach you everything about SEO - or any other aspect of the web. I suggest you read Google's basic guidelines - https://support.google.com/webmasters/answer/35291?hl=en&ctx=cb&src=cb&cbid=1h0dcl2owc3c2&cbrank=0 - and download their Search Engine Optimization Starter Guide from the link on that page. Work your way through them, and then if you have any specific questions which have not been answered, please feel free to come back and ask again, but please do some basic research of your own first.