Anyone can participate if they meet a few requirements first.
Redditgifts is open to adults 18 and older worldwide. We have an FAQ on the sidebar of the subreddit that explains how everything works. If it sounds like something that you would be able to do, you can head over to Redditgifts to create an account. Once you've created an account, linked it to your Reddit account (you must have a valid Reddit account in order to participate) and verified your email, you'll be eligible to participate in exchanges.
We have a calendar located on the sidebar of r/secretsanta that shows when all of the exchanges take place, but not what they are. Exchange themes are not announced until the day that signups for each batch open.
If you have the box checked on your Redditgifts profile to receive email notifications of upcoming exchanges, you won't miss a thing!
For tips and procedures, please see our Redditgifts 101 series.
Please note that multiple accounts are not allowed and you can only sign up once per exchange. The number of different exchanges you can participate in at one time is based on the number of credits you have earned. Everyone starts with 1 credit.
Matching happens at different times of the sign up close date for each exchange. This generally happens between 8 a.m. and noon Pacific so be sure to sign up and link your account and validate your email address before the close of sign ups. Email verification can be slow when the system is busy so please don't wait until the last minute to sign up. This could cause you to not qualify for matching.