Login if you're an existing user, or sign up and create an account if you're a new user.
If you need to create an account please see the below guide.
Once you have logged in go to My Account located in the top right of the screen.
Click on Manage Subscription.
Select Card Details.
Under Add a payment method select Direct Debit.
Click on Pay with GOCARDLESS and a new window will open. From here input your sort code, account number, address and then click on Set up Direct Debit.