set up virtual server on adsl modem router but....

i am using adsl modem router and now i wish to set up a website so i have applied a dynamic-dns
but a problem that is i must set up a virtual server in my router through its utility but i can find a "virtual server" tab when i access to configure the setting of my router...

so if there any software that let me set up a virtual server?

or anyone know forums that can post my problem on it??

my english is bad .....................sry for unconvenient..