In Freecell Collection you can customize the background in many ways.
Texture - With this you can select a texture of your choice. Many textures are available arranged in groups like Bricks, Bubbles, Marbles etc.
Colors - You can select a color from a set of pre-defined colors. A fade background option is also available.
Pictures - A picture can be selected as background from a set of available pictures.
Color Schemes - With this option you can create your own background color by adjusting Red,Blue and Green values for top and bottom edges. You can also save this as a new color scheme.
Custom Images - You can add your own images and use them as background with this option.
Image Folders - Here you can specify a folder with images and select any image from that folder as your background.
You can also set a timer to change the background at pre-defined intervals like 5 seconds, 15 seconds etc.
You can set the background as tiled with Tile Background option provided the background selected is a picture.