Well, first you have to finish your dohook

The village case is somewhat ... empty ...
case "village":
break;
Try doing and addnav in the village case.
addnav("Poke Mart","runmodule.php?module=pokemart&op=whatever");
Then, you put the run in there, IE, what the page does and says to the user/server.
So, you would start off something like this:
function pokemart_run(){
global $session;
page_header("Poke Mart");
$op = httpget('op');
if ($op == "whatever"){
//include code here
}
page_footer();
}
and so on..You can look at other modules for examples at how to do it right or how to include multiple pages.