Lucella,
Are you sure it needs oil?
The lube oil level indicator (aka dip stick) was usually on the engine left (driver) side and had a yellow ring for a handle. They were in three possible places along that side. Front, Mid and Rear. Have light as sometimes it is hard to see the tube with the stick out. It should be marked "Full, Add and Maybe Add2".
I only saw these engines when they were not in a vehicle, but all the 6.8 Fords that I dealt with had the oil fill on the right (passenger) side cam cover. The cap had yellow markings. For some applications, the the fill was remote with a hose, but always on the right side.
Do not add a whole quart if the level is not at the add mark. This family of engines does not like being over filled.
Give DH our best. He has a rough road to manage. He is lucky to have a good wife with him.
Matt