Forum Posting Problems!
 

I really need some help, here! I post on a forum and recently, I've gotten this:

http://pimpandhost.com/image/31650142-original.html

I tried to fix this myself by going to the Plugin page. This is what I've got:

phpBB Plug-in installation:
Unzip and then upload this file to your phpBB forum root directory.
Make backup of /includes/template.php file
This file will change /includes/template.php and make new file pahUploaderForm.php

I don't have a clue where to even FIND the "forum root directory". Can anyone help?! Thanks, in advance!