Checkout following xaml hope this will provide some guidlines to u
<grid x:name="LayoutRoot" background="White" xmlns:x="#unknown">
<textblock fontfamily="Arial" width="400">
<linebreak />
<run foreground="Maroon" fontfamily="Courier New" fontsize="24">
Sample
</run>
<linebreak />
<run foreground="Teal" fontfamily="Times New Roman" fontsize="18" fontstyle="Italic">
Text
</run>
<linebreak />
<run foreground="SteelBlue" fontfamily="Verdana" fontsize="14" fontweight="Bold">
Run
</run>
</textblock>
</grid>