Instructions
Visit the official Habbos website, and log in to your account.
Visit the page that contains a list of Habbos Retros pet codes. Highlight the desired code, right-click and scroll to "Copy".
Click on the "Catalog" page, and press the "Pets" tab.
Scroll through the pets using the left or right arrow button. When the screen displays the animal you wish to color, right-click inside the "Name" text-field. Scroll to "Paste".
Press the "OK" button.
Drag your pet into your room. Drop it in the corner of the room.