Because this is a compressed file (7-Zip format), you must first the images before you can use them. Step 1: Extract the File
a tool like 7-Zip (Windows) or The Unarchiver (macOS) . Wallpapers1836.7z
"Wallpapers1836.7z" and select "Extract Here" or "Extract to [Folder Name]". Because this is a compressed file (7-Zip format),
Do you have or a similar tool installed to open the file? Wallpapers1836.7z