how can i make a "Rate this" option to my website? for example the one you see at various download sites and you have the option to rate the download by clicking the "star" did you guys get me?

Really that would mostly be done with a server side script (ASP, PHP, etc), inserting a value into a database. The JS portion of it would probably be an XMLHttpRequest to send the request in the background, without having to reload the page. Check this out:
http://www.yourhtmlsource.com/javascript/ajax.html