Do the same thing you did when you first marked the gift received from your exchange page. Make sure you are logged in and go to your manage exchanges page found here:
- Click on the exchange you are managing.
- Click on the "Thank Your Santa" button.
- Add as much information as you want, along with as many photos as you want.
- Click on the "Save and Publish link.
Your Santa will get an email letting them know you received their gift with a link to the gallery.