Routing traffic to a central gateway?

Question

VPN

Hello, there are 2 vpn offices between them that wraps local traffic (192.168.1.0/24) (in the central office there is zywall 300 on 2 zywall 20 offices), one kind person set up RDP to which you need to go from 2 offices to the ip center. office.
How to properly wrap RDP so that the connection is with a cent. office? I'm not really familiar with routing.
I visited routing to indicate that ip 46.4 ... redirect to 192.168.