When you first log in, you will see a screen like this one: to set up your payment preferences please follow these steps.

Click on the Add Now button on the Complete Account Setup shown in the section highlighted on the image above (or you can click on the Avatar next to your name in the top righthand corner to access this too).


Here you can opt between Store Credit (given in the form of coupon codes for future purchases) or paypal. 

 If you opt for PayPal, you will see a field to enter the paypal email address, please enter this then click save.