Hi.  I dabble on and off with Photoshop Elements 3 and working on a complex images using various rendered images out of Carrara 6 pro.  What I want to do is composite the pieces in Photoshop using various layers.  I understand the basic layer functions.

 What I want to know is: Can I use a grayscale image as a mask which would allow me to take out parts of one of the images without hours of erasing by hand?

Secondly, if it is possible how do I set it up using the layers?

Thanks for taking the time to help an inexperienced user out.

Sincerely,

David