Our wallpapers are made in different resolutions and maybe you will find that some of them are not suitable for your monitor. Anywyay, not having same wallpaper and monitor resolution doesn't mean you can't still use the wallpaper.
Therefore please check the resolution comparison bellow in terms of monitor aspect ratio's.
|4:3||640x480, 800x600, 1024x768, 1152x864, 1280x960, 1400x1050, 1600x1200|
|16:9||1280x720, 1360x768, 1366x768, 1600x900, 1920x1080, 2048x1152, 2560x1440|
|16:10||1280x800, 1440x900, 1680x1050, 1920x1200, 2560x1600|
If you don't find exact matching resolution, then you can choose any bigger resolution in the same aspect ration.
Best wishes and Merry Christmas to all