OK since you had not even a comment I may as well Critique. YOu want the bg to be done, so here we go! The Grass: You could have added a little more of it, the yellow comeing through looks kind of like its a child's grass (not really that childish, just someone drawing grass like this for the first time.) or you were plain lazy. Trees: There pretty nice, not quite as good as I'd expect from you, but still good. I like the yellow leaves and what you did with them. River: It looks like you go tired of making the river and quite halfway though, I know rivers get narrower but that one goes from like I I wide to I I wide.
BACKGROUND CRITIQUE TIME! I'll take this piece by piece ;v;
OVERALL Pros: I love the color palette you used, the soft colors make the piece easy to look at ;u; Your use of the marker tool in SAI is very nice, too. I like your use of light and dark to make the far-away trees seem far (sorry, no other way to explain it xD).
Cons: Your brush strokes look very piece-y. Yellow is showing through behind your grass, and the body of your tree looks incomplete. To fix that, add multiple layers of strokes to create a depth effect. Also, your strokes shouldn't bend around in ovals. They should be smooth and fluid, especially when doing the water.
What to keep doing: Keep using the marker tool! Your style is very lovely. Keep coloring the back of your canvas a light color. (In traditional art, this is called "washing your canvas. It's so white doesn't bleed through to your finished piece. Definitely continue, especially when using the marker tool.) Continue using the colors you are. The palette completes the piece. Keep practicing! I'd love to see you continue.