You're about the 999th person who asks me this. I only used the basic features of punbb, no templates or language files or anything like that. I grabbed the code I needed. You have to be into PHP and MYSQL if you want to make that work. There's a lot to be modified, and its impossible to give you a step by step how-to.
You can use the extern.php file of punbb to get the active topics list, but if you just know the very basics of PHP and MYSQL, you should be able to easily do it yourself.
Don't be discouraged though; when I started out with all this php stuff I was messing around with a very simple script not knowing anything about php and mysql (I did know about HTML), and learned along the way. I suggest you try the same thing. Get a simple messageboard( punbb of course ) - or similar script, and start messing with it. However, if you don't know the basics of HTML I suggest you start with that first.
You can check www.hotscripts.com for scripts, but there are more sites out there of course.
Im not sure what you already know, but if you are a total beginner I'd suggest this:
1. Do a HTML tutorial. And do it all in NOTEPAD, not dreamweaver. You'll become a 1337 HTML'er who knows what he's doing. It'll save you a LOT of time to fix errors and stuff. There have been quite some dreamweaver-fella's who needed help with the most simple errors on their websites. Start using dreamweaver when you can write all the basic html in notepad.
2. Find a nice PHP+MYSQL script with something like a message submit into a database. Whatever you don't understand you will find in any basic PHP/MYSQL tutorial. Mess with it, change stuff, see what happens. If you're at this point and get stuck, you can ask me for help if you want.
3. Try to recreate stuff.
Trial and error will make you good, no matter how much tutorials you read. But you already know that of course.
Good luck,
Goober