Help with Solver function

Hi,
I am using 2007 version.
I am trying to calculate the correct shift schedule based on the efforts for that time.
I have enclosed the xls sheet where I have already calculated the followings
A. Column D contains the efforts for the time mentioned in column A ( this is for the month of Feb
B. Column F contains the required number of staff for that 30 min. For example between 00:00 to 00:30 , I need the 0.69 FTE ( Staff) to process the data

Now I want to use Solver function ( if there are better ways, I am open to suggestions) which will help me to give the optimal shift pattern.

Can you please help me with this? I have enclosed the sample xls.

Regards, Sanjiv