Thank you much
Yeah, here's the file you want:
http://www.ohloh.net/p/phpbb/download?filename=phpBB-3.0.4.tar.bz2
download it (don't unzip it!) then upload it to your site via CPanel -> file manager or FTP
Put it in the folder Public_Html
highlight it and press the extract button
Then you just need to go to yoursite.x10hosting.com and it will ask you a few questions.
The important part is the database. You will have to create the database in CPanel -> Mysql Databases. Call it whatever you want, probably phpbb or forum, something easy. Then, in the same tool, create a user, again name doesn't matter and a password. I recommend using the generate password button because it makes very secure passwords and you don't ever have to type in the password after installation. Copy the password. Then, add the user to the database, again in the same tool.