To upload a card you designed in a design software like Canva, or upload a design someone else made for you, you'll want to follow the instructions or watch the How-To video below.
Click "Add Quick Send"
Select "Editable Postcard"
Click "Show Blank Templates" on the top of the editor
Once the blank, white templates have loaded, you'll select the size postcard you designed
Click the upload button on the left side of the editor (It looks like a little line with an arrow coming out of it)
Upload the front and back images you created
select the front image
click "Insert" at the bottom of the upload pop-up
Resize by dragging the corners of your design to fit the template
Repeat for the Back