Are you using Square Cash or Square POS? there are a number of steps you need to take if using Square POS.
Here is a guide on getting started with Square POS https://squareup.com/help/us/en/article/5123-square-get-started-guide
Here is a guide for Square Cash https://squareup.com/help/us/en/article/5187-get-started-with-square-cash
