Inputs for a Mac

I'm running mac 10.4, on a macbook. I usually use the input port on the macbook, plugging that directly into a guitar. In garageband i can record using the guitar, using the "built in input" option. however, when i use this in ninjam, i don't hear anything. and when i try to join a jam, i can hear everyone else fine, but there's no way for me to make any noise through either reaper, or ninjam... any help would be appreciated. I seem to have fixed it now...it just works 0/0

Can you record in Reaper? (Ignore NINJAM for now.)

I;ve actually resolved this problem. thank you. and yes i can.

Good, because I do note have inputs. :P