Starting GUI Desktop

I have installed Oracle 9 client on 32-bit machine for Linux Enterprise 2.4. After complete installation and testing the oracle client.
After rebooting the system I was presented with a login prompt but the GUI desktop does not come. I tried startx but that did not work. What command would I use to be able to choose, and after that, start the GUI. Also can i set environment variable also. Any suggestion in this regard will be highly appreciated.
Thanks.