The Online Payments feature allows you to easily set up how your online payments work.
You can navigate there by going to Settings "⚙" > Online Payments.
Once there, you can then turn on the feature by clicking the button:
When you turn on the feature, you should see a screen like this:
Once here you can click any of the buttons to turn on the corresponding ability.
You can also set up the Default Money Account here:
An important note about this feature, you will see two transactions for each payment in the account assigned to the event. The first will be a deposit for the total amount of the payment. The second will be a debit for the total amount of the credit card processing fees.