The set contains the following wallpapers:
Aquarium - underwater scene, ordinary resolution, 3 panels wide
Harvey Balloon - forest and mountains, 4x resolution, 10 panels wide
Joja - Joja logo, ordinary resolution, 6 panels wide
Joja 2 - Joja logo and slogan, ordinary resolution, 6 panels wide
Night Scene Maru - night sky scene, 4x resolution, 7 panels wide
Night Scene Maru 2 - night scene with trees, 2x resolution, 10 panels wide
Sebastian Mountain - night sky with moon, 4x resolution, 20 panels wide
Sebastian Ride - moon with trees, 4x resolution, 7 panels wide
Tropical with Boat - palm tree and sailing boat, ordinary resolution, 2 panels wide
Tropical without Boat - palm tree and ocean, ordinary resolution, 2 panels wide
For the wider wallpapers, it's okay to put them on narrower walls.
Technical
Requires Content Patcher and Custom Wallpaper Framework.
If you want to complain or ask for help or help me test my mods, you can visit my Discord server.
A list of all my mods for Stardew Valley is available at https://www.nexusmods.com/stardewvalley/articles/895.