2D Wallpapers: To download the full size wallpaper, click on the image.
Snowy Ground Christmas Snow
Hot Summer Beach Outdoor Swimming Pool
Spring Hills Bamboo Park
By the Sea Farm
Halloween National Park (recolored)
Springtime Beach
How to use Custom Wallpapers:
Download the wallpaper like you would do any image on the web (right click on the larger image and choose Save Image as... ), and here's how you use it in the GoPets window.

Within your computer, open the 2dimg folder that's within the GoPets Ltd folder found in Program Files. (To do this double click on the My Computer icon on your desktop, double click on your local disc which is probably labled C:\, double click on the folder called Program Files, then double click on the folder called GoPets Ltd. Inside the GoPets Ltd folder is a folder called 2dimg; double click on the 2dimg folder.) Inside that folder are all the nameplates and the default wallpaper from the game.

The default wallpaper is called countryroad_1024.jpg. Make a backup of the default wallpaper and move the new wallpaper you just downloaded into the 2dimg folder and rename it to countryroad_1024.jpg. When you close and reopen GoPets, the window will show the new wallpaper because it's been renamed as the default wallpaper.

Make sure you don't have any wallpaper in the little wallpaper square of the GoPets game, or the new wallpaper won't be visible.