Hmmm…. new artist. You are trying a lot of new things at once here… One thing that might help would be to take it simple. Just do one pony, get the anatomy down, then roll with punches but um… I have to say the background you did was actually decent if you just began with this artist scene. I’m pretty new myself to the drawing scene. I tried just using the pen tool in paint tool sai. This is the result.
 

 
Yeah, I learned tweaking the paint tool makes sketching so much cleaner. Just sharing what I know, and I am new, so take it with a grain of salt.