Configure the serial backhaul.
Connect your router serial 0/1 (or whatever) to the neighbor 0/0 to the right. Connect your 0/0 to the neighbor to the left. Note: Not all the routers have both sides so you may be lucky and only have one friend.
Use 172.16.13.N where N is your network for the 1/0 interface. Use 172.16.13.100+N for the 0/0 interface.
e.g. you would 172.16.13.7 and 172.16.13.107 if you are 7.
mask is 255.255.255.0.
Try using the clock speed 56000.
You should be able to ping both interfaces but you may need to add ACL to allow it. Consider this a trusted network though so you don't need rule sets.