I just downloaded terragen classic and played around with it for an hour. This is what I came up with. PLEASE give your criticism; I know it isn't very good, you will not hurt my feelings no matter what you say about it.
Looks good to me. The hills and water look fine and so does the sky. You could just try to get rid of the slightly misty look and sharpen the image some more.
The balance/ratio of water-mtn-sky seems pretty good to me. The colours are divergent and therefore interesting. You want sharp in the foreground and hazy in the distance as that's what we normally see in mountains even on a sunny day. In comparison to other images I've seen produced on this same software I would not have known you had only an hours experience.
Looks very good to me, the only think I would advise is maybe adding a bit different color to the mountains..to add a bit more life to the image. Nice work though!
I like the landscape and the water is wonderful. It is a little pale in colors and I would like a little more contrast and colorshifts to add a little more life. I think it is a very good first try in my humble opinion!