Here is a simple example of using the Style element. Defining a style is similar to using a cascading style sheet to define styles. In WPF you can do much more with styles though. I am only going to show a simple example.
Look at the example below. The Border element has its style defined inline. I define a Style just for my Border elements based on its existing properties:

After your style is defined, you can now set it to your element:
<Border Style="{StaticResource TitleBorder}">