How do you install a sky or background in a model?

I am new to Sketch up and a landscape architect in NJ. The images you posted look amazing and I would love to achieve that level. Can you walk me through your process. I am using Auto Cad. Thanks for your help and great work.
Marc
marc_nissim@yahoo.com

Hi All
I am a Landscape Architect in NJ. I want to begin using Sketch up for my presentations. Can someone please walk me through the best way to begin a drawing and bring it in from Auto Cad. If anyone is in NJ and wants to tutor me I would welcome the help.

Marc