Question

Hi there, I'm new to Photoshop and icon making. I've been trying to follow tutorials but one step has always stumped me. I want to bled some imgaes in an icon. The tutorials say paste this layer on that layer. I'm not sure how to do that because the edit selection doesn't have "copy" highlighted, and when one image is selected its the only one visible on the layer pallate. Can anyone help me? I realize this is a really stupid question.

Thanks so much!