Hi Tim,
The repeating event for tis is described as an iCalendar event below. Save the text as a plain text file (i.e. not rich text etc.), with the title AP_day.ics . Then open it with the Finder. This should open iCal and ask which calendar you want it in. Administrative Professionals Day should be added to that calendar for dates from 2010.
If you can supply a reference to the other dates you are interested I'm sure a similar thing could be done for those.
Best wishes
John M
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Apple Inc.//iCal 4.0.4//EN
CALSCALE:GREGORIAN
BEGIN:VEVENT
CREATED:20110425T183532Z
UID:F459D6AF-516A-4236-85C6-ED74DDB2F5DD
DTEND;VALUE=DATE:20100422
RRULE:FREQ=YEARLY;BYMONTH=4;BYMONTHDAY=21,22,23,24,25,26,27;BYDAY=WE
TRANSP:TRANSPARENT
SUMMARY:Administrative Professionals Day
DTSTART;VALUE=DATE:20100421
DTSTAMP:20110425T185422Z
SEQUENCE:)
DESCRIPTION:By John Maisey\nwww.nhoj.co.uk
END:VEVENT
END:VCALENDAR