Now-Studio has the same User Interface pattern on all screens. Once you understand how to create a new record on one screen, it should be very straightforward to do the same on other screens because they follow the same general pattern.
The Create Button is located on the top right of every screen. For example, if you want to create a new Subscription Plan then:
Similarly, you can create new Customers, Staff Members, Staff-Shifts, Limited Time Memberships, Private Sessions, Class Packs & Retail Products. This button is also used for scheduling a new class and a nonrecurring event. Moreover, if you want to make a new purchase for your customer then click PURCHASE and select the product you want to purchase. Alternatively, you can make a purchase from the Purchase tab.