Use one of these http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_Suction-Gun-Performance-Tools_9240026-P_N3401C_T%7CGRP2082_____#to refill the diff as there is no way to pour the fluid up through the fill hole. With the vehicle level, fill until oil begins to run out of the fill hole. Once it begins to spill out give it a minute or so to drain. Once fluid stops running out it is filled to the proper level.

-Jim

Thanks, if he's a newbie, I want him to know some of the simple tricks for safety just in case.