The first few pics I ever edited together, not that good, but still leanring how to use GIMP If you reply could you tell me how to improve, thanks. Anyway, here there are:
It looks like you used alot of blurring in the first picture, try keeping the blur in one direction (up and down) and not every way possible. The second picture looks fine, and with the third, the same applies to it as with the first picture. Keep practicing with it, they'll improve as you keep working.