virtual router running Debian - add gateway to LAN

Hi All, 

I'm new to this list, I want to thank you all for support in advance. 

I have a router running Debian with one interface facing public and 2nd interface to a LAN 10.5.0.0/24. 

I have a 2nd router one interface on 10.5.0.0/24 and 2nd interface facing another LAN 10.6.0.0/24. So I want 10.5.0.0/24 to be able to access 10.6.0.0/24. I did the following for a temporary work around. 

ip route add 10.6.0.0/24 via 10.5.0.6 dev eth0

this works fine but if I log in to another machine in 10.5.0.0/24 network, I'm unable to access 10.6.0.0/24

can you please help? I have Linux 3.2.0-4-686 Debian 3.2

Thanks in advance!