These Images are lit only with an HDRI map. (there is no direct light in the scene)
Crits and Comments welcome
Thanks
Cecil
I like it.
But I would have brighten up the shadows, and swapped out those trees for something else.
Nice contrast.
Bobby Parker www.bobby-parker.com
Nice start
I would tune down the direct light a bit and lighting up the sky light too just alittle bit
Check this article /tutorial I think it would help you :
http://www.chocofur.com/hdri-maps-in-blender.html
and change these trees plsss 
Regards,