While there is most likely not really any practical reason for changing the Finder background, it is possible to do. If you’re really into customizing your Mac it’s a simple process to add a background image or change the solid background colour.
Firstly changing the background is only available while Finder is in the icon view. So if your view settings in Finder are set to Coverflow, list view or column view it won’t work. To put Finder into the icon view simply select the left most view setting, or press the Command Key and “1”.
While in the icon view of Finder, select view options from the View menu in the Menu Bar, or press the Command Key and “J”. Doing so will bring up the view options, where you can change the background. The background options are located at the bottom of the view options window.
Selecting “Color” will allow you to select a color and the picture option will let you drag an image into the “Drag image here” box. You can also select “Use as Defaults”, when you’re done customizing and it will set it as the new default for all folders. There are also a few other options here than allow you further customize your folder.
I tested out the Picture setting and found that the image does not stretch or move, so if you scroll to far down, the image will end and you’ll see the default white background. The only fix I can find is to use a larger image. Also the “Arrange By:” has to be set to “None”; use the “Sort By:” instead, or the background options will be greyed out.
In my opinion using the “Color” setting is superior to using the Picture setting simply because no matter how far you scroll down in Finder, it’ll be the same color you selected instead off cropping off like an image does.
To get rid of the background and go back to the defaults just select “White” under Background. After the default is clicked press the “Use as Defaults” to apply it to all folders.