HOW DO I UPDATE THE PURCHASE ORDER STATUS (URGENT)

http://tinypic.com/view.php?pic=n2iqf8&s=8#.VM1Z_WjF-TQ

How do I update the Purchase Order Status from originally "Pending" to "Processed" when user click on the Accept PO button ?  Btw the Pending is hardcoded in Database.


Btw when user clicks on the select, the Purchase Order details will be shown using DetailsView shown. What do I have to add in the code behind in the AcceptPO button? Btw I am using 3 tier and web services for the project. Do  i need a web service to update the Purchase Order Status?