dhcp config - 2 subnets on one phys net

[Igor Antokhin]

Sorry for a question from a newbie, but I could not find a clear answer to 
mu problem - only pieces of the puzzle...

I have a computer on a physical network 195.208.220.0. It runs Linux 
Fedora Core 5. It is just a client machine not providing any general 
use services like dns printing etc. Now for some reasons I want to create 
a private network for my department using the same physical ethernet.
I understand that what I have to do is this:

1.Install a dhcp server (done).

2.Create its config describing two subnets - one 195.208.220.0 in which my 
dhcp server will NOT provide any address range (I simply do not have the 
authority to do that); and the other one e.g. 192.168.0.0, with the range 
for dhcp clients say from 192.168.0.100 to 192.168.0.254. Define both 
subnets within a shared_network evironment. Done.

3.Accociate my private network with an alias of my network card eth0. 
e.g. eth0:1. Done.

4.On dhcp clients, use the address of my computer in that private 
network, e.g. 192.168.0.1 as the gateway. (actually this should be done 
automatically).

5.Assign my computer the ip 192.168.0.1 for the interface eth0:1. Done.

6.Set up my computer as a router for the internal private network 
192.168.0.0 (serviced by eth0:1) - that is, enable forwarding of the 
packets between the two networks.

6.Set up NAT to properly masquerade packets from the private network.

Now, I don't know how to do the steps 5 and 6. Also, I am not sure if I 
did not miss something important in the general layout. Please advice!

Thanks for your help,
Igor