Changing the image on the portal homepage based on the user

Hi Experts,

We have a requirement where a single portal is being shared by two different customers/vendors.In this case when the users of these vendors use the portal we want to display the image of the respective vendor on the portal home page as the branding image based on the user logged in from the respective customer/vendor.

How do we do this?Please explain in detail.

I have referred to this link

http://help.sap.com/saphelp_nw04/helpdata/de/6e/8590f1d6d349c9adc34c6a8085189b/frameset.htm

But can some expert explain in detail with a good example for writing the rule if it is the correct way.

Please suggest.

Thanks,

Rajani Nandagiri