You really need to get a copy of the Driver's Manual of the state in which you live, and then read it.
You do not need a CDL for a cargo van, unless you will be hauling HAZMAT (for which you'll need a CDL with a HAZMAT endorsement) or more than 9 passengers for hire or more than 15 passengers not for hire (for which you'll need a Passenger endorsement).
Panther, however, requires a CDL for cargo vans despite the fact that they will not put HAZMAT or passengers on a cargo van. You could get a Class B with no endorsement and you're good to go. But you're better off getting a Class C with a HAZMAT endorsement for Panther, because if you have a HAZMAT endorsement, even though they won't load you with it, your contract will pay higher with the endorsement than it will without the endorsement.
Do you remember when you got your first driver's license, and they made you take both a written test and a road test? You needed the road test to prove you could drive the vehicle for which that license allowed you to drive, that being cars and light trucks. When you get a different driver's license, you'll need to do another road test for whatever that license allows you to drive, in the case a cargo van. HAZMAT precautions and procedures will also be a part of the road test (hint, stop at all RR crossings).