You will need to have 3 subnets.
Lets say you have 1 PC and give it an IP address of
192.168.1.60 with a 255.255.255.0 subnet mask.
Give the second PC an address of 192.168.5.20 with a 255.255.255.0 subnet mask.
Presumably you are going directly to the E0/0 interface of the router and not through a switch. If that is the case make the E0/0 interface of the 1st router 192.168.1.61 255.255.255.0 and attach PC1 to the interface.
The second routers E0/0 Interface you could make 192.168.5.21 255.255.255.0 and attach the second PC to the interface.
If you are attaching the routers via the FA interfaces then do the following:-
On the 1st router make the address for the FA0/0 interface 10.8.0.5 255.255.255.252 and on the second router make it 10.8.0.6 255.255.255.252 and attach them together.
You can have a look at the routing tables on the routers now to see if the defaults show the networks.
Logon to the router and type
router#sh ip route
If the end networks are not visible then the easiest thing to do is add static routes to the required networks. Dont forget to add a return route as well.
To read how to configure static routes visit