If you want to customize the appearance of the standard WPF Button with our Free Office 2010 Blue, Black and Silver themes for WPF then you need to do the following:

1. Add a reference to the Theme assembly.  In Solution Explorer, right-click on the project node and click Add Reference. Browse to the VIBlend.WPF.Theme.Office2010Black.dll, VIBlend.WPF.Theme.Office2010Blue.dll or VIBlend.WPF.Theme.Office2010Silver.dll and click the ‘OK’ button.
2. Drag and drop a Button control from the VS toolbox.
3.  Load the Theme resources and set the Style property of the Button control.

 <Window x:Class="WpfApplication98.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <ResourceDictionary Source="/VIBlend.WPF.Theme.Office2010Blue;component/Button.xaml"/>
    </Window.Resources>
    <Grid>
           <Button Content="Office 2010 Blue" Style="{StaticResource Office2010BlueButtonStyle}" Height="30" Name="button1" Width="125" />
    </Grid>
</Window>