Re: Modifying header to display image issues
Ah GeoCities, how i miss all those animated GIFs 
Well mate, if you’re up for the challenge I’d start at something like http://www.w3schools.com/ (HTML, then CSS, then PHP sections). 9/10 it’s learning by doing and asking when stuck.
Also, I’d strongly suggest installing and playing around with WordPress before bbPress. It’s not a requirement at all, but they’ve nailed the separation of Presentation, Data, Logic so it’s easier to know where to edit – while in bbPress it’s all still bundled in together most of the time – making it hard to know where to edit if you’re new.
Effort will get you very far with bbPress though, it just needs to “click”. Don’t be a stranger 
Kev