Well in that case you are more than likely connecting via DHCP. Some things you can try:

Open a console window (the clam shell icon in the taskbar) and enter netcardconfig for the network card configuration tool and agree yes to dhcp and you will see messages in the window to tell if it has been successful (if not post the error). Also in the console window ifconfig eth0 will tell you the settings of your ethernet card. You can also use the ping command to see if you can contact the internet eg. ping www.google.com or ping 216.239.39.99 which is google's IP address. Whatever errors if any you get post them.

Also be a little more specfic as to the steps you have tried eg. I turned on the computer and booted the CD when I enter some address in Mozilla and try to connect I get this error blah blah ... that sort of thing will help to get it working.