In order to fix this to get system updates and any packages, you need to set Yum up.
This is massively easier than it looks.
Ensure your OEL system can reach the Net e.g. via
wget http://www.google.ie or some such.
We need to get the public repo details so
It should download the repo file to this directory.
Assuming you want the latest build of everything, you are done, as the latest repo is by default enabled ; otherwise edit the repo file to enable the version you want
Then it's just yum update.
* Note el5 is different for el4 and el6 of course.