It is quite simple! The first step is to get the postcard into an image file. For that you must have access to a computer scanner or a use a digital photo camera. Once you have the postcard in an image file, follow these steps:

1. If you are not logged in to Postcrossing, log in.
2. Go to your Received postcards section
3. Find the row that has the postcrossing ID for the image you would like to upload. Click on the green '+' icon found in the last column of the row.
4. Click the browse button and find and select your file. You can also enter an optional description about the postcard.
5. Click Upload and that is it!