OK, I'm not sure where you are in this process, but you need to follow the instructios in the wiki first. Just go through the standard install just the way it says. Add thoes lines to a htaccess file in the example.com folder. Once you're done with thoes instructions, you'll be using your own version of php4 instead of the default one on your server.
Now you'll need to edit the php.ini file. That should be in the php directory (in your home dir) so you'd type something like:
nano -w /php/php.ini
Then you can press ctrl-w to bring up a search, and type in fopen. Turn that value on. Press ctrl-o to save the file, and ctrl-x to quit. Now your script should work.
This should work for you, however having never done it myself I might be wrong.