The property panel will display options for Wall Style and Wall Color. Style and Color are combined to create a highly customizable wall surface. Click on the Eyedropper button to change the style or color.
The size of the style texture can be scaled with the Texture Scale option.
After the desired style and color are set, click on the wall to change its texture. Note that walls are two sided and different textures can be applied to each side of the wall.