How to join an existing table that has starting date and closing date to the existing calendar table to calculate working days

How to join an existing table that has starting date and closing date to the existing calendar table to calculate working days .

My calendar table looks like this :-

dt  isweekday   isholiday   Y   FY  Q   M   D   DW  monthname   dayname W
1/1/2010 0:00   FALSE   FALSE   2010    2010    1   1   1   6   January Friday  1
1/2/2010 0:00   FALSE   FALSE   2010    2010    1   1   2   7   January Saturday    1
1/3/2010 0:00   TRUE    FALSE   2010    2010    1   1   3   1   January Sunday  2
1/4/2010 0:00   TRUE    FALSE   2010    2010    1   1   4   2   January Monday  2
1/5/2010 0:00   TRUE    FALSE   2010    2010    1   1   5   3   January Tuesday 2
1/6/2010 0:00   TRUE    FALSE   2010    2010    1   1   6   4   January Wednesday   2

and the other table containing start date and end date looks like the following :-

orderid orderdate   ordercloseddate actionby
40978   4/15/2010 12:47 4/18/2010 14:47 tjjohn