Better would be to refer the mother board manual. It would have step by step procedure to do it. Make sure you dont try to update it using the Asus Windows Application to update the BIOS from Windows itself as i had a bad experience with it.
Download your motherboard user guide - > http://dlcdnet.asus.com/pub/ASUS/mb/socketAM2/M2NPV-VM/e2806_m2npv-vm.pdf
It has the step by step instructions on how to update the BIOS, and it also has screen shots.