Comment 4 for bug 366459

There are several ways, I generally use the command line, but if you prefer the GUI method, it is pretty straightforward.

Click System at the top of the screen, then, from the drop down menu, select Administration. There you will see Synaptic Package Manager. Click that and enter your password into the box which will appear. Once you have given the password, you will be presented with the Synaptic Package Manager. Under Settings, there is a Repositories button - click that and then untick the entry for your CD-rom.

To update your system after this, click the Reload button on the main Synaptic Package Manager screen.

Any problems - please shout.