You can set up your payment method by going to your Settings page > Get paid > and click on Add Payment Method. From there, you can choose which payment method best suits you.
To answer your next question, yes, it is important to file the W8BEN form. This form indicates that you are not a U.S. person, and will not be paying U.S. taxes. You should be able to complete it by adding your legal name, and your address.