How to use ResourceDictionary of WPF,,When we use simple windows form and add only usercontrols of wpf

Right Click the project in the Resource folder:
Add->Existing item->Select the Resource file

You can use following line of code to include resource file.

< Window.Resources >
        < ResourceDictionary >
            < ResourceDictionary.MergedDictionaries >
                < ResourceDictionary Source="sample.xaml" / >
            < /ResourceDictionary.MergedDictionaries >
        < /ResourceDictionary >
</Window.Resources >

By using key value we can access resource.
Use this function
this.FindResource("Key value")

Check this link
http://msdn.microsoft.com/en-us/library/aa350178.aspx