In the designer, select the control. In the Properties window, click the lightening bolt button to display the list of events that the control can raise.

In the Code Editor, create a method with a signature that is the same as the signature of the event that you want to handle.

Double-click the entry for the event to create the default event handler. This creates the method with the proper signature, and the Code Editor opens to the new method.

Add the code that you want to execute to the new method when the event is raised.