Sessions help please

Hi, I am going to use sessions to authenticate and protect my pages, this is what I have so far... User logs in via form, this is checked via a SQL call, if the correct username and password are entered I run the following: session_start(); session_register("UserName","Password"); header ("Location: Http://www.domain.com/members/index.php"); The bit where I get lost is 1) how to authenticate this on each page and 2) How to close the session after the browser has closed. I have tried many tutorials etc but none seem to go into great detail in those areas. Anyone know of any decent tutorials or any snippets I can learn from. Thanks