Christine,

You have to watch the bulletin board for an announcement that someone is going to run a new round robin. Then get your name to the organizer as soon as possible. Mention that you a new chipper to increase your odds of being selected in case there are too many people seeking to join the round robin.

If you are selected, you will eventually receive a bunch of chips in the mail. Each RR has their own rules, but basically you will be able to take as many chips from the RR as you want and replace them chips of at least equal value and condition. You will then be responsible for mailing the RR, usually by Priority Mail with delivery confirmation, to the next participant.