Including a custome header

Hi everyone,

I'm building a community website and thought about integrating PunBB to it. But I have this little issue that I would like to clarify. This may be a lengthy question list. But I'd really appreciate if someone can help me out.

Ok, my website is primarily PHP and each user has his/her own username & password. This login process is handled with a session_start() in the header. What I need is to integrate a user's login to my website with that of the PunBB forum. In short, when a user logs on to the website, he/she should automatically be logged in to the PunBB forum as well. Is this possible? If so, how do I go about doing that? How do I register a user in my website and in the PunBB forum at the same time? And how do I include my header file, which has my logo and the sets the session info, on top of the PunBB forum?

I'm not a pro in PHP or web development. Still in the process of mastering all these web technologies. So I'd be really grateful if someone can demonstrate what I should do with a code sample.

Thanx in advance to anyone who's ready to help me.