1. Under "Your addresses" in your customer account, you can modify your delivery addresses or add new ones.
Here you can also specify default delivery addresses, which saves you time during the order process.
2. You have also the possibilty to change your adress after your ordered in your order confirmation e-mail. Take a look at "YOUR INFORMATION" and click "Edit Shipping Address".
Tip: Update your addresses before you order as delivery and invoice addresses cannot be changed once an order is on the way.