Hello Anapret16-gmail-
Welcome to the Community page,
Are you trying to add a user on the Quickbooks app on your iPad?
If you are could you log into Quickbooks on a web browser google chrome and then go to the cogwheel top right and then you should see the option for manage users to click on and add a user. You will definitely see the option if you're the master admin of the product.
If you still have issues let us know.