You can easily control and configure the wallpaper with a simple user interface. To open (or close) this GUI click on the tray icon that appeared in your task bar after launching the program.
Note
You can use all mouse buttons to open/close the GUI. I'd like to implement a popup-menu, but for some reason it just doesn't work.
The GUI should look like this:
You can do the following things in the GUI:
ui-control ui-configuration
For information about color modes (which you can also configure in the UI), refer to Color Modes.