Add Background Color to Listview's Specific Row

Goal:
Change the listview's background color to light colored grey if the current time pass the appointment time. For instance, the time is 10.15 and you have background color for the 09.30 - 10.30 and 10.00 - 11.00.

Problem:
I do not know what syntax I need to use in order achieve the goal.

Information:
- I'am using Nhibernate to retrive the data.
- This is a usercontrol.