Not too bad for a newbie. Good sky, good fog, decent variation of trees, and you even used custom grass models. However, your sun is very unnecessary for this terrain due to the dark sky/fog. The sun makes no sense in such a dark atmosphere. As far as tiles go, your road looks very jagged. Be patient and straighten-out your road by selecting the smallest tile placement square and fix it up. You lack tile variation as well. Throw in some Dirt and Grassy Dirt to help make it looks less plain! The use of only two tiles is noticeable - in a bad way.
For hills, you did a pretty nice job. But keep in mind that there is a Smooth tool for hills to help make pointy/sharp hills look more well-rounded and... smooth. Smooth hills are good! Pointy hills are bad in nearly all cases except for when you're making mountains or cliffs.
And since you're new, just a head's up, NEVER USE TERRAIN CLIFFS! They're ugly and no one likes them.