If you want to join a congregation, your first step should be go to the list of congregations and their contact information on this page: Find A Congregation. Search or scan through that list to identify a congregation that is in or near your area. With each listing you will see email addresses, social media links, and other ways to contact the congregation.
To join a congregation, you will have to apply directly to that specific congregation. Different groups have their own membership requirements, and may or may not be accepting new members at the time you are interested. You should reach out politely to find out if they are accepting applications, and find out what their application process is like. Please remember always to be courteous, and that you are not entitled to membership in any of these groups. For more information about what congregations are, and their relationship to The Satanic Temple “umbrella” organization, read: What is a TST Congregation?
After you reach out to a congregation in your area using the contact information on the Find A Congregation page, please be patient. Remember that TST is an all-volunteer organization: some groups only meet once a week, and some groups meet less often than that. You may receive a reply within 24 hours, but you shouldn’t be surprised if you do not. If you make a couple of attempts to contact a congregation and receive no reply, it is possible that the congregation is simply not accepting new applicants at this time. You can always try again later in the year. In the mean time, you may want to look into whether you would like to volunteer for a Campaign instead.