not bad for your first. the edge where the land meets the water is too abrupt, there's no 'shore' or edge dug by the river. I think the dot-texture in the trees could be replaces with something that conveys volume better, more clumps/layers of foliage. the dithering isn't necessary. scene is a bit plain, maybe add a woodland critter or some rocks or shrubs or something. as a final note, you may find the WIP forum a more useful place for constructive criticism than the gallery.