If you are the store manager, Shop Manager is your workplace. Here are the tasks it makes most sense to get comfortable with first.
Get started with
Products — create and maintain items, prices and categories.
Sales — keep track of sales orders, invoices and customer history.
Purchasing — order goods in with purchase orders, receive them, and handle purchase invoices.
Reports — produce the reports you need to follow operations (remember: all can also be produced as Excel).
A good pace
You do not have to learn everything at once. Start by creating and selling a couple of items from end to end — that gets the whole flow under your skin, and the rest falls into place.
Read more in Sales, Purchasing and Products.