HELP! Mail Merge! I'm an idiot
 

OK I know this must be the simplest thing to do, but having lost my assistant I find eight years of college useless when it comes to word processing.

How do I do this..I have a mailing list in Excel...I want to do a merge such that when I print it, each individual address will print on the letterhead paper in the space that when folded, will appear in a window envelope for mailing. Hope that makes sense.

TO my defense, I have figured out to runa merge and print but only I have to feed envelopes throught the printer, and that's what I am trying to avoid. Thanks in advance for your instructions or resource for performing this function. Ive looked everywhere, but am too dense to find the answer!