I have solved this problem.
First, u can base on the build-in skin to modify on this web site. This is very useful tool, so it should be put on somewhere we can see easily on the this web.
After u have created a new css style, set yr tab property
|<link href="../Styling/TabStrip.my.css" rel="stylesheet" type="text/css" />
|<telerik:RadTabStrip Skin="my" EnableEmbeddedSkins="false" ......
Then all things should be good to go.