Overlapping UV on Static meshes

Newbie: This is driving me nuts. I have created a simple model using BP brushes. I convert the model to a static mesh and place them into the game. When I burn lights, I get an error: Object has overlapping UVs. Enable error coloring to visualize. This also happens when I bring in models from other applications.

How do I enable error colorizing?
How do I add a new channel?
How do I fix this error?