It's a pretty good start for your first time through the tutorial. Couple of things I noticed, and these are meant to be constructive criticism's, not bashing.

1) You have a river that runs from coast to coast with no obvious source, that to my knowledge can't happen. The rest of the rivers look good.

2) IIRC it seems that the gradient used to give the basic land colors is off a bit, the transitions don't seem as smooth as they should be.

3) It looks like you may have skipped some steps in the hill and mountain portions of the tutorial - it's been awhile since I used it. I'd suggest going back thru the hill and mountain steps to see if in fact you missed/overlooked something.

4) Your forest appears just to be a solid color and has no texture or layer affects applied.

Keep at it, you'll get the hang of it after a few tries.

@Gregorus Prime - IIRC in this tutorial the lighting comes from the Southeast instead of the Northwest (which is the default for most software), I believe that's why the drop shadow appears backwards.