There are several places in the system you can create products. One of the most frequently used is when you click in the blue Admin Toolbar on Products > New Product.
Another frequently-used area is under Products > Products > New Product (the blue button).
Another area worthy of mention here is the + button in the Register, next to the item search area.
You can also create products from within Work Orders, Purchase Orders & Receiving Orders, and from the Categories page under Products, when viewing a category or subcategory.