Visual Studio Class Diagram not showing relationships

It's for people like me who do not find where is the menu item in 1 minute.

This combines with Visual Studio and does everything you want to do with Class diagrams. http://modeling.codeplex.com/

In Visual Studio 2013: right click the class, click Add, and select the desired relationship.

More information: http://msdn.microsoft.com/en-us/library/ff657806.aspx

When you right click on the field or property you can select show as association or show as collection association.