PHP Fatal error: Call to undefined function session_register()

session_register() has been DEPRECATED as of PHP 5.3.0 and REMOVED as of PHP 5.4.0.

Your facing this problem because of you are using PHP 5.4.0 or above

Read PHP documentation
http://www.php.net/manual/en/function.session-register.php


For solution : Remove  session_register() from you code.

Cannot send session cookie - headers already sent warning message in php

If you are getting warning in php file that "Cannot send session cookie - headers already sent".
For solution you should insure that nothing is being sent to the page before the session_start().

Make sure its a plain ANSI file, not utf-8 or anything.
if it is not ANSI file then open notepad, insert the php code, and save it as plain ANSI. It should work fine.