Customization is really not bad once you get the hang of it. All the template files are in /bb-templates/ and the main ones you will most likely want to change will be:
There are other ones, but with header.php you can put in your links to other parts of your site or anything else you want displayed on every page. This can include your images. Footer.php is where you will put in more information on closing your style tags you opened in header.php and your footer information. Front-page.php is where the meat of your forum is, whether you want to move around the hot tags or just want to add in a link to a plugin off the main page.
The real meat and potatoes of customization is done through CSS in style.css. That is where you can tweak where you want things placed and what colors you use. If someone knows CSS, you will find it not so bad!
Once you change a file, what you want to do is create a folder called /my-templates/ and add the edited files there. That way, if you make a mistake, you can delete the file off the server to fix it and bbPress will go back to using the one in /bb-templates/ until you upload to /my-templates/ again.
The future will have a system much like WordPress, a kind of drop and drag themes approach, but we have this for now!
The starting point would be to read:
That should get you going. Once you understand changing around the stylesheet in style.php, it doesn’t seem so bad!