When creating original characters, it's very important to consider where that character would fit into the show's universe. If your character does not fit in, you should probably consider a redesign.
Sure, I'll ask for one if you are looking for the chance to draw more ponies. Also don't get discouraged. I'm just wondering though, are you modifying existing pictures? It does look like that could be the case (I'm sorry if not). If you are I think there are techniques that can be used to more smoothly do that, though I'm don't know them well, and I don't really know the features of Paint.net
Your art is a little raw but I can see potential. Best thing is to keep practicing. That said, I'll request a drawing of my OC Rockette. Spoiler: Reference Rockout's kinda partial to the high ponytail when he's a girl so other than that do with him what you will.
Sorry I've been off for a while. During break I was visiting graduate schools and traveling allover. On return I've been working on a project. It was meant to be a request, but I'll draw for you if you'd like. That said I have a free art board already.. though the line is somewhat long and I haven't finished a drawing for it in a little while. That said if you are okay with something quicker and not colored I could maybe try to do it sooner.