From the Form Design window, go to View > Code. Now you can enter code for
your form, and all the associated objects.
A more organized way, and an easier way, is to allow Access to do some of
the syntaxing for you. Right-click the object, and choose Properties. Then
go to the Events tab. Select the event you wish to modify, click the down
arrow and choose Event Procedure. Then click the '...'. This will take you
to the code window, already labeled for the particular event you chose.
Sharkbyte