You have the idea of how to lay out a sig, background, foreground, layers and all of that. I know you just started and you damn fine job for just starting.
I think what was meant by "software impared" was that you arent fully grasping all that gimp has to offer, I dont know anything about it but i belive Leal uses it? im not sure, but i know there are a good amount of people who do use it. You have to try experimenting with other features and effects for backgrounds. Right now yours are fairly simple, you put a pic in the background and then use the brush and color over with that, you can do so much more than that to help your sigs look even better. Keep at it and over time youll get a knack for a certin feautre that you like to use and will have great looking sigs.
No one is trying to put you down, were all just trying to help