To add new price plans and user groups into the software you would need to install and enable the Enterprise Pricing addon within the following admin tool:
ADDONS > MANAGE ADDONS
Once done you will see the "add new price plans" button as you see in the following screenshot:
Once you click the add new price plan you will see a choice where you need to choose the type of price plan: subscription or fee based.
Within the above screenshot you see:
Inserting a price plan into the system does not automatically mean that people will use it. For a price plan to find use it must be attached to a user group and of course users in that user group. Any pricing a user group sees is based on the price plan(s) attached to it.