Cubic Explorer comes with some Themes already buid-in. To change the Theme go to the list of available Themes with View > Theme.

To install a new Theme you'll need to load it into CE first. Do so by choosing "Load Skin" at the bottom of the View > Theme list. Chose a *.skn file and it will be loaded and displayed in the Themes list. Now Select it and you're done.

You can get new (user created) Themes from the Customize section of the Cubic Explorer Forum. Some of those may get released in later versions of CE.

If you're interested in making you're own Themes, you can do so by using this free software. You are encouraged to publish your CE Themes in the Forum as well. (Note that the *.ini-files, which this program produces have to be renamed to *.skn to work in Cubic Explorer)