Mac Time Machine/Time Capsule

I use the Time Machine application to continually back up my iMac onto the Time Capsule (a handy little gizmo that provides wi-fi as well as backup).

I also have a MacBook that gets its wi-fi from the Time Capsule. So far, I haven't backed up the MacBook, although before I turned off its Time Machine I'd get pop-up messages to the effect that I can back it up but it will wipe out the iMac's backup.

Is it possible to use the Time Capsule to back up both computers without losing the info from either one? If so, how?

Thanks, Medi! I'll take a look at the manual.

Edited to add: I looked at the manual, but I can't find any information on using the Time Capsule to back up two computers—only how to set it up to back up one computer. I must be missing something.