[RWP] Noob help

[Crystal Dennis]

Hi!  I am a super noob to mixing and just installed reaper and ray
access.  It looks like it's supereasy to use (I've been playing with
training mode, haven't recorded anything in it yet) but I've been
having a problem:

I want to be able to play the backtrack I use in reaper then record
over it, and go back to do harmonies and stuff etc. but everytime I
hit record after loading the backtrack into reaper it doesn't play:  I
was wondering if there is a preference I need to click or something?
I have been looking around reaper but can't find anything.

Also if anyone has a list of ray access commands that would help me a
lot too!  I have been googling and looking through the manuals and
haven't been able to find any hotkey command lists for reaper.

Thanks,
Crystal