Welcome, Larb! You've stumbled on the best site dedicated to the creation of RPG game mapping. Post some of your maps - hand-drawn, PSP maps and anything you've begun experimenting in CS3.
You may want to consider GIMP, an open source (free) image editor like PSP and CS3 - we've got lots more tutorials here for GIMP, rather than CS3 - but we got tutorials for Photoshop as well.
Its best to post whatever you got, in whatever status it currently is - then let us offer advice and tips.