I know very little about creating macros myself, but attaching one to a
button is easy enough.
Once you place your button (or drop-down list, or checkbox, or whatever) on
your form, you can then right-click on it and select "Properties". Here, in
the Event tab, you can attach a macro to the button whenever it's clicked.
Just use the drop-down list to select an existing macro to a specific event,
or you can click the "..." icon next to the drop-down list to bring up the
Macro Builder.
Notice you can also have macros or events execute for all sorts of events,
ranging from simply waving a mouse over the thing you're working with, or
double-clicking on it, or all sorts of other options.
