Login on IIS

Hello! I need to use login form when user opens my page so this is for session. Then i need to get userno from usertable for input user and pass, because userno is almost in all tables. Then i need to put userno in cookie (or i guess). I think i need to do something like this in every php script: include('login.php') or require('login.php') But i only want to show login form, read data from it and somehow continue loading script normally, i dont want that login form stays above all my page. How to do this? Thanks, Radovan