It looks like your using GIMP cause of the molten effect....is that right???
Anyway my advice since you are just starting off is to focus on just doing test images with out putting any text in it for now!!! Text seems like it would be the easiest aspect of a sig but it is in fact the most difficult!!! Dont worry about text for now and focus on focal placement, blending images as well as colors, and focus on the basics like how to size properly!! I like the idea you were trying to go for and I think with the basics like sizing, sharpening and bluring, and color blending, it could be a pretty cool sig!!!