After you've determined which size envelope you need (more info), select the color or style that you want.

You'll then be given the option to customize your envelope with a return address. To do so, choose your desired quantity and click the "Start Personalizing" button.

You'll have 4 lines to enter your desired your custom info in the Editor. Editing the fonts and sizes however you want:

Then, click "Next" to review your proof and add to cart.