Alright, after repeatedly banging my head against the wall, I gave up on using phpBB3 as my base and installed IP instead. Great program!
I still want to change the header. Lopalong was nice enough to give me advice in another thread on how to do it for phpBB3, and mostly it's correct. Here is the original thread: http://www.icyphoenix.com/viewtopic.php?f=32&t=4640
I did these actions:
Uploaded and changed both images.
Made adjustments to the css as advised.
I am unable to locate a file labeled as overall_header.html in IP, though.
This is the result: http://bearfootgold.com/forum/
You'll notice that at the right edge of the header there is a gap and the header itself overlays the top links a bit. I have found two overall_header files with an extension of .tpl, but don't want to mess with them until somebody that knows what they are doing (as opposed to my general method of breaking things until I fix them) has input.
Also, I'd like to change the title, keywords, link off the header image, etc. Right now it states "yourdomain.com". Again, which files need to be modified?
Sorry about all the questions, totally clueless in general but this is waaaaaaaaay beyond my skillset.