There is, I believe, a patch/upgrade to PHPBB that allows file uploads. Is your site hosted by a third party (i.e. served off space allocated to you by your ISP)? If so, they will prbly have someone who can help if you email them. If you host it yourself, its manuals time. I'll try to have a poke about for you ... used some other forum s/w but never PHP, but they are all much of a muchness :)
Also, please be aware that allowing file uploads potentially opens your site to a world of malicious hackers who have nothing better to do other than break into your web site becasue they can, so you need to be careful. The main thing is to only allow files with specific extensions to be uploaded, e.g. .MPG, .WAV, .JPG &c. ... and def not anything ending .PHP - or death!
Feel free to PM me if you want to take this offline, with the caveat that I might not be able to help, but I should be able to point you in the right direction at least :)
