I am assuming that my most straightforward and simplest option is to provide a menu of actual physical links as choices that people can use to head off to on the site, after login? Rather than trying to provide some form of script that automatically diverts them to some page of my choice, once login has been successful?
If I were, however, to want to pursue the auto-diversion tactic of sending them somewhere specific on a successful login, where would be the best place to insert such a set of commands (given this particular programmer's rather low skill set in these matters!)?
(I have also downloaded your amended script onto the local folder so I don't accidentally and at some future point rewrite your corrections).