Add a Click Event for a Control in a Custom Form Page
You can use VBScript to extend the Click event of a control in a custom form page.
Open the Script Editor.
How?
For the control to which you want to add a Click event, for example, a command button control, add the following. In the example, CommandButton1 is the name of the control.
Sub CommandButton1_Click End Sub
Enter the code that you want in the event.