You can make a PHP portal without the knowledge...

check out PHP Fusion, Mamba, Xoops

Or Joomla
http://www.joomla.org/

Joomla is great!

You might also have a look at e107. It's a pretty decent CMS.

There's also PHPnuke, Joomla/Mambo is the best IMO...

Your host got Cpanel and Fantastico? Then you don't need to know much about PHP as that will install the whole lot easily.
I prefer PHPNuke Platinum which is an enhanced version of PHPNuke. But you can go have a look at all the CMS versions and check out demos of them. I did with another site I was popping up... PHP you can learn along the way... ;)