Build your try-on box with up to three frames: choose a color in the dropdown, then click add to box. Your frames will appear in the right sidebar (or scroll to the bottom on your mobile device to see box contents as you build them). Use the numbers there to remove frames from your box, if you change your mind.
When you're happy with your selections, click add box to cart. and you'll be automatically redirected to complete the check-out process where you'll choose a See & Select Center for shipping.