You should have received an email from URA communicating your new TIN and details needed to create an account. i.e. Form Type, Registration Effective Date, and Pass code.
Incase you were already registered but have not received this communication yet, please contact your tax district or send a query through the web portal.
In case you received the email, but lost your details before creating an account, please send a query through the web portal and you will be directed on how to get another pass code.