Well, first you create a table, tblHolidays. Then you add the two fields HoliDate and HoliName. Make the Datatype for HoliDate a Date/Time field, Short Date. HoliName is just a Text Field. Then you put in all the holidays you need to deal with in this table with their dates. Then you copy and paste the function DeltaDays() into a new module in your database. Name it funDeltaDays. Then in your query that has the two dates put this in a new column
NumDays: DeltaDays([StDt], [EndDt])
Put the names of your date fields where you see [StDt] and [EndDt].
That will count the number of work days between the dates excluding weekends and holidays.
Post back if you have any problems.
Paul