Forward the traffic of one public ip to other public ip

HI!

I am new to mikrotik router we are using mikrotik 450 board, We need to forward the traffic of one public ip to other public ip. For example

First public ip : 203....
Second public ip : 125.
... ( global network ).

The inbound or packets to first public ip is forward to the second public ip..

First pubic ip → second pubic ip ( in bound)
second public ip → first public ip ( out bound )

Please any one help for this…

http://wiki.mikrotik.com/wiki/Manual:IP/Firewall/NAT#Destination_NAT