Changing color is not easy with most of the skins because they use images to accomplish their styling. See the different skins here http://demos.telerik.com/aspnet-ajax/panelbar/examples/functionality/firstlook/defaultcs.aspx
(Click the Skins drop down in the upper right). I believe the Simple skin is the only one that you can style with css. Otherwise you can this tool: http://stylebuilder.telerik.com/
to edit skins.