1. Configure an inside interface.
ip nat inside
ip address192.0.2.1 255.255.255.0
2. Configure the outside interface.
ip nat outside
ip address 203.0.113.1 255.255.255.0
3. Configure an access-list to define which devices can be translated by the dynamic NAT and exclude any devices that you do not want dynamically NAT'ed, such as servers that are part of a static NAT.
ip access-list standard nat
Deny ip host 192.0.2.28
Permit 192.0.2.0 0.0.0.255
3. Configure a global pool that is the IP or range of IP's to which the inside addresses will be translated. This IP will be in the subnet of the outside interface or the outside interface IP. If you are using only one IP then that is the first and last IP in the pool.
ip nat pool global 203.0.113.1 203.0.113.1 netmask 255.255.255.0
4. Type the following command to tie everything together and start dynamic NAT. It also configures PAT by the overload command allowing one outside IP to be used for many internal clients.
ip nat inside source list nat pool global overload