If the tab control's content is defined as a dialog resource, use the Visual Studio dialog editor to change it.
If you want to programmatically change the tab's text, read up on the CTabCtrl.
http://msdn.microsoft.com/en-us/library/essk9hbw.aspx[
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Bind (or Attach) a CTabCtrl to the actual HWND. Use GetItem/SetItem to change the tab content.