Kya x3!!! Very cute :3!!! But it looks like you colored with normal paint o: so here are some suggestions for better coloring programs:
GIMP: completely free and easy to use once you get used to it. You can download many brushes and use layers (which help a lot). In my opinion quite similar to Photoshop, although I never used Photoshop before xD
Sumo Paint: haven't used this to color yet, just found this. You don't have to download. This also has layers. Not much to say on this >.>
For easier coloring do this: Once you have your drawing on one layer, right click on the layer and click 'add layer'
Make sure the layer is transparent and click 'ok' to create the new layer.
Go to the layer bar again and you'll see the layer attribute (it'll probably say 'normal') click on it and change it to multiply.
Start coloring your drawing and you'll see that the outline stays on top while the color goes behind ;3 allowing for easy coloring.