[northwinds]

I know this is fairly basic but I haven't used M-powered properly for a while so.......
Trying to do a bit of Saturday afternoon recording, and after laying down some basic drums I plug in my guitar, enable record on the track, check the sound and hit play - but nothing.
I can hear the drums on the other track but the guitar is silent.
If I hit record instead of play then great I hear everything, but my inspiration goes out the window with red light.
I just want to play along with the drums for a while until I get some ideas straight and not have to stop and undo the recording all the time.
I know this is an easy one, but I can't remember and just want to get on.
Anyone please?
BTW I'm running 7.3.1 on an M-Audio FW 1814.
Many thanks.