I am not sure what exactly is not clear to you in the mentioned project. This is why I will try to elaborate on the approach that is used.
If you take a look at the Resources.xaml file you will see that there is a Style targeting the SettingsPaneView. That style predefines the Template of the SettingsPane. This is how the customization is done. Note that in the customized Template there is a RadTabControl which hosts the tabs. Following this approach you will be able to define the RadTabItems (and their content) as you need.
I hope that this information will get you started with the required customizations.
Pavel R. Pavlov
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