Well, if as you say, you have more than a passing familiarity with Photoshop, I would suggest looking at the Tutorial section. While they may not teach you anything new about the program, They will about how to apply its various abilities where they apply to mapping.

Your input in the WIP threads would also be welcome 'cause there are quitr a few people just starting out with that prog.

Welcome and have fun!!

See you in the WIPs