Theme is editable through existing control panel which can be found if you go to “Appearance” -> “Themes” on admin panel and activate Olxer theme. then click on customize link next to theme. on opened page you can change color for some parts of theme. It is same color changing panel which is visible on demo site.
To change further you can use custom CSS as explained here: http://classibase.com/forums/topic/change-background-color-in-theme/#post-1266
Olxer theme is for ClassiBase script only. All themes are included and full source code available when your purchase Classibase script. Classibase themes will not work on Osclass.