From the left hand menu, select the Teams & Roles tab
Choose Users from the categories across the top
Add the email of your team member and level of permissions you would like them to have.
The Owner permissions gives access to editing and viewing everything in Merchant Portal, Manager level permissions allow your team member to edit the shop hours and edit the menu, but they are unable to edit the banking information in your account.
Your team member will need to create an account on joe, then go to their email and accept the invitation to the company to be able to view the dashboard.