Es simple, con variables $_GET:
Código PHP:
<?php
if(!isset($_GET['section']) || (isset($_GET['section']) && $_GET['section']=='bank')){
#BANK SECTION
if(isset($_GET['action']) && $_GET['action']=='save'){
#BANK SAVE ACTION
}else if(isset($_GET['action']) && $_GET['action']=='delete'){
#BANK DELETE ACTION
}else{
#BANK MAIN SCREEN
}
}else if($_GET['section']=='employees'){
[...]
}
?>