Mohammed,
Go into interface configuration mode on the outside local interface (the one facing the Internet). Use the 'ip nat outside' command to make it the outside interface for NAT.
Go into global configuration mode and create an access list to encompass your 1.1.1.1 and 1.1.1.2 networks. For example, you could use the following command (although the wildcard mask can certainly be modified to decrease the number of available addresses).:
access-list 10 permit 1.1.1.0 0.0.0.255
Assign the access list as the NAT inside source on the same interface that is facing the Internet using the following command in :
ip nat inside source list 10 interface Gx/x/x overload
Note that Gx/x/x in the command above simply refers to the interface facing the Internet, your's will not have the letter x, and will only start with G if it is a gigabit connection. I'm also assuming you have already assigned the public IP address to the connection facing the Internet, and private IP addresses have been assigned to the other two devices.
If you need any more assistance, let me know.
Good luck,
-Mike
