After downloading your photo, resize it to 4096 x 2048 pixels.

In SideQuest click on File Explorer and select the Pictures folder then:

Click the [+] button and create a new folder called 360,

Click into the new 360 folder,

Click the [+] button again and select your photos.

Your custom photos will now appear after the standard images in the game. Images should be saved as .png or .jpg files max: 4096 x 2048.