How do you book a VIP room on a train from Nanjing to Shanghai?

There are two ways.
1. You can go to the Nanjing Railway Station and tell the ticket seller that you want to buy a first class seat.
2. You can also search here https://www.travelchinaguide.com/china-trains/ and then book the tickets of first class seat online. Then the operator will contact you and deliver the tickets to your hotel or the address you leave to the operator.