I would highly recommend that for questions like this, how to use a .NET class or WPF functionality that you Google your question to other sources than this forum. The reason is that .NET is a Microsoft technology and there are many examples of how to use the various classes on other web sites and within the MSDN documentation.
For example, the link here explains how to handle a Menu control in WPF and provides examples in C#. These examples normally translate directly into COBOL but if you require help with the translation you can post your questions here.
Thanks