Keywords usage for page ranking ?

Keywords are to be used throughout the site to get listed in search engine results or only on homepage would work ?

Not sure what you mean but you can use keywords on any page to rank.

You are suppose to use the keyword throughout the site, in contact me, about me, etc.

Your homepage should have around 1000 words spread over 3 posts, don't use the keyword too much, and make sure it's reader friendly, people take like <2 seconds to close a page if it sounds like shit.

Hmmm, you can probably make more money using hubpages and squido lense, but whatever.