Hey
I like your Lighting...and good placement in terms of land...
Only Two Things..
1: Try Setting Higher Detail levels...They seems to be a bit low in this picture.
2: What Did you use for your Snow, As It Seems to me, Somewhat Unrealistic.
Otherwise...Great Start, I would recommend having a look about the forum (the Sticky in Terragen 2) Which has lots of stuff to help you get used to and better with TG 2
Enjoy!
Zionner