How to start a forum?

Hi there, i am developing this website that is suppose to have a forum, it is my first approach to implementing forums and have no idea of where to start… All i know is that i want the website NOT to have an external forum, i sort of want the kirupa.com style forum, where the theme of the page continues on into the forum… can anyone direct me into a tutorial or point me into the right direction of how to “embed” forums into the website??? and suggestions for which type of forum to use (phpBB??)?? cheers!