Since you appear new to the digital art world, one thing that definately comes in handy in Photoshop is called an adjustment layer.

Photoshop is very overwhelming at first but the more you use it the more comfortable you'll become with it. You'll also become more comfortable with it's many tools that you can apply to a layer (filters, curves, levels, etc.) Most of the time when you apply these tools they are a one time thing, you apply it and you can't readjust it...it's done.
But there is something called adjustment layers, with this you can apply some of your favorite tools as a seperate layer that will affect everything below it. But the cool part is that as you compose/paint/add to your artwork you can go back to that adjustment layer and make changes to that layer tool as you work...so you aren't tied down anymore to what was, you can adjust the layer as you proceed.

I know the idea and concept of what I'm talking about is probably greek to you but keep it in the back of your mind and when the time is right...look it up. They are the best.

Good luck and hope this helps.
Ray

Comitted to excellence through art.