I recently downloaded an Iberia A320 to FS2002 and it works great. Is there an easy way for a beginner like myself to change the paint job of that specific A320 to one other than Iberia's, say AirCanada for example?

Thanks in advance.

I would suggest Tom Gibson's Repainting tutorial for starters:

http://www.calclassic.com/repaint.htm

Basically, what you want to do is take the Iberia textures, and repaint them as Air Canada.  Of course it's a bit laborious, but persistence pays off.