Hee hee hee hee - you want to add a forum to your portal huh? Luckily this is entirely possible - however I dont know everything about it.
The easiest way to do it is this: Set up whichever lovely free opensource php forum you think is suitable somewhere. Doesn't matter where, as long as it works.
Then, get horrid awkward Oracle portal release 2 and put a HTML Portlet (should come with the product) on the page you wish. Then put iframe code into the HTML portlet such as that below:
<iframe width=100% height=500 src="http://yourserver/yourpath/yourscript.php?yourparamater=yourvalue (if necessary) ">This
browser does not support iframes </iframe>
With the URL of your php forum in the place indicated above. This will bring your forum into the portal to all intents and purposes, though of course it will actually be running elsewhere.
Hope this helps - anything more integrated escapes not only me but a hell of a lot of other people. LOL.