i want to direct traffic port aaaa fram the wan interface tot the vlan host bbbb
Cisco NAT is not always the easiest thing to get the hang of !
The key thing to understand with the static NAT statement is that it is bi-directional ie. it the statement works both ways.
So perhaps thinking of it like this may help -
ip nat inside source static tcp cccc bbbb interface FastEthernet4 bbbb
the above tells the router to present the inside address of cccc to the outside as the address on the fa4 interface. Note that inside and outside are relative in that it is purely down to which interfaces you designate as inside and outside.
So what you are telling the router is that if a packet comes from cccc and is destined for the WAN it will be translated to fa4 address. But you are also telling the router that any packet from the WAN coming to the fa4 address should be translated to cccc on the inside.
Key thing to understand is the concept of inside/outside, have a look at this doc which gives a good overview -
If I understood correctly you want that traffic received on wan interface for a specific TCP or UDP port to be directed to an internal host with a specific ip address.
I suppose you are using NAT you can add a specific statement for this
ip nat inside source static tcp local-ip local-port interface global-port
if you are not using NAT you can use PBR to achieve this
Hope to help