Actually, found this on the net, this may help explain it a bit more:

PICKING A THEME FOR YOUR CIRCLE JOURNAL
You may pick any theme you would like for your circle journal. Once you have your theme, you need to pick a journal. I am not going to specify a size for your journal – please choose whatever size you would like to work in, or feel comfortable with. Just remember, it has to be mailed around, and the larger it is, the more the mailing will cost. I would also suggest a journal that is spiral bound, as these are easier to work in, but
whatever is your preference. Please be sure that your theme is stated, and explained if necessary, somewhere in or with your book. This will alleviate any doubts.

THE CIRCLE JOURNAL PROCESS
Everyone forwards their snail-mail address and e-mail, them the hoset will forward a mailing list. We will mail our books out by a set date each month. In other words, you will work in your book and then by the set date, you will mail it to the person below your name on the mailing list. You will then receive another book, work in that, and mail it on the next set date. (Yes, you CAN mail a book out earlier if you're finished with your spread.) You will always be mailing to the same person.