Share 'How to respond to ATC Buddy Jam?'

How do I respond collaboratively to the ATC Buddy Jam card I just received? It was in a mail art packet I got, and labeled as such. There was a picture on the front of the card and a space for two names and addresses on the back, with only the first name and address filled in. Do I add to the picture, add a friend's name to the second space on the card, and then send it to the first name on the l…