TMG 2010 on Multiple VLAN

I have configured TMG 2010 with 10.24.22.15,subnet mask 255.255.255.0.Default gateway:10.24.22.1.

The computer with the same vlan able access the proxy server. But when I connect to other IP range users are unable to access proxy server.

my current network

Vlan 1: 10.24.23.1 subnet mask 255.255.255.0 default gateway 10.24.23.1

vlan 2 :10.24.20.1 subnet mask 255.255.255.0 default gateway 10.24.20.1

vlan 3:10.24.22.1 subnet mask 255.255.255.0 default gateway 10.24.22.1

How can I add route add to the TMG server to client to access the proxy server. Please advice.