Traverse date picker controls and compare two date in the date picker using background code

Hi 
I have 6 date picker controls at the front end and each pair represents the static finish date and the actual finish date of a specific task. 
What i want to do is to traverse all the date picker controls in the form and compare the actual finish date  to the static finish date. If any of the actual finish dates in the datepicker control is greater than the static finish date, I will set the indicator value to 0. 
How could I do this using the background code? Thanks.