To create or contribute content to a tome, you must have a user account. You can sign up from tomehost for an account. Alternatively, if someone invites you to contribute to a tome, you will be sent a link that will allow you to create an account and join a tome.
Above: Registration requires the bare minimum information
Passwords in the database are salted and hashed, meaning that we have no way to recover your password if you forget it. However, there is a reset mechanism that will send and email with a temporary link that can be used to reset the password.
At present there is no mechanism to change the email address of an account. Since all emails are verified (to ensure you cannot sign up with a fake email address, or an address that does not belong to you), the procedure for this will require you to contact tomehost support to request a change.