I need one for my website, or just any tutorial to do one.

These may help.

http://www.free-php.net/

http://www.emailmeform.com/

thanks a lot for sharing..I'll check immediately

I think that a comment script wouldn't be that hard to make from scratch. You just need to handle the comment data that is posted, ensure it isn't spam (maybe use akismet or some quality score?) and then store it in a database. If you know basic PHP/MySQL, it should be trivial.