Nautilus has basic configuration capabilities, one of which is the ability to change the background of the view pane (the large panel on the right). To change the background, select the Edit menu and "Backgrounds and Emblems..."
This will then bring up the Backgrounds and Emblems dialog. You can select a texture or a color. To apply a texture or a color, select one and then drag it from the Backgrounds and Emblems dialog to the Nautilus' view pane.
You can find more information in Help, Working with Files -> (s6.8) Modifying the Appearance of Files and Folders -> (s6.8.5) Changing Backgrounds.