appt-add is an interactive autoloaded Lisp function in `appt.el'.

(appt-add TIME MSG &optional WARNTIME)

Add an appointment for today at TIME with message MSG.
The time should be in either 24 hour format or am/pm format.
Optional argument WARNTIME is an integer (or string) giving the number
of minutes before the appointment at which to start warning.
The default is `appt-message-warning-time'.