copy/paste questions

I managed to copy part of an email and pasted it onto the desktop (of my Mac). Now I'm at a loss as to how it can be inserted into a forum.If I drag & drop it from desktop to the "your message" box on DG it just pops back to the desktop. If I select it for "choose file" a box comes on saying it needs to be jpeg or something. This machine is testing me, and its winning. Is there any solution to this, or is it a matter of retyping the list from the start??? I realize iMacs are in the minority, but they are so darn cute.