Static NAT requires few configuration steps. Each static mapping between local and global addresses must be configured. Not unlike a static entry for every static IP address required. You must inform the router on which interfaces to use NAT. Interface subcommands inform the router which interfaces are inside / outside.

1. ip nat inside command on an interface to specify inside.
2. ip nat outside command on an interface to specify outside.
3. ip nat inside source static inside-local inside-global from global config to configure the static mappings.
4. inside local will be a LAN IP - inside global will be your public IP (an EXTRA public IP).

Create an access list to match a group of source addresses as needed – why else would we overload?

R1(config-std-nacl)#permit 10.1.1.0 0.0.0.255

R1#sh access-lists 
Standard IP access list NAT
    10 permit 10.1.1.0, wildcard bits 0.0.0.255 (2 matches)
    20 deny   any

Then configure NAT to match against entries in the NAT list configured above. Specify OVERLOAD to enable PAT.

ip nat inside source list MY_LIST int fa0/0 OVERLOAD