If you don't already have one, you can create a free Square Account. With Square, you are charged for online payments at 2.9% and $0.30 per transaction.
Important note for users outside of the USA: You will want to set your currency in the Booking Settings BEFORE you do your payment gateway setup and your first test payment.
To see which currencies are supported, read here: Using Other Currencies
To set up Square:
Go to the Manage Payment Gateway, then Select the blue Use Square Button next the Square option.
When the pop up appears, enter your account login details for Square. This will conect your Square account to your Booking pages.
If you have questions about setting up Square Payment in the builder, or if you get an error when doing your test transaction, please reach out to email@example.com for assistance.