I've just gotten an iPad2. I've downloaded some photos from my PC and plan to upload from my own camera when I get the necessary connector kit. However, I can't figure out how to access photos in the iPad with apps designed to edit and otherwise process photos. The only ones available are those taken by the iPhone camera itself.

I can double click individual photos in Drop Box and they will appear on the iPad screen but I can't do anything with them.

What am I missing pls?