There is a UserControl, naturally being a DependencyObject'om for which you need to create your DependencyProperty like this:
<my:TLBUserControl HorizontalAlignment="Left" Margin="230,25,0,0" x:Name="tLBUserControl1" VerticalAlignment="Top" />
HorizontalAlignment="Left" is the DependencyProperty. How to do it most correctly. Leave good articles on this topic, and even better code samples. Thank you in advance for your help.