I just mailed my stuff out to John! I'll try to help you guys out with the SASE thing--I think I may have the hang of it now (either that or I'll just confuse you more, hehe) Anyways, here goes:
*Get two 9 x 11 envelopes (that's the size that I got at least.)
*Address one of the envelopes to John, and the other to yourself. You're gonna need two stamps for both envelopes...the lady at the post office told me that anything that's bigger than a regular letter needs at least two stamps, even if it's not that heavy.
*Fold the envelope that's addressed to you in half, and put it inside the envelope addressed to John.
*You may also want to put a thin piece of cardboad inside the main envelope to prevent any bending, etc., and just stick a post-it note or something on there asking John to send it back in the envelope addressed to you (thanks for clearing that up for me earlier, Kathryn!

).
*Now just make sure you're letter's in there with everything else, and send it out. Voila!
Haha, I hope I didn't end up confusing anyone more...Good luck!