new to sessions

escuse me the keyboard in Tallin airport

i work on http://panbaltica.com/docman/action_popup.php

i have one session_start which causes 2 errors
i send headers not to cache the page then the session_start - it
should be elsewhere it is a test - anyway, i want to create the
sesseion and stop caching of the page

i had somethiing which worked but i cannot recreate it

since i am new to session vars any ideas anyone?

wbr
sonnich