Session variables on custom modules
In submit of form store your data in session variable $sid with _drupal_session_write('mysession', $value); and in every where you want read it with _drupal_session_read('mysession');

you shold start session before you write or read session variable like php.

drupal_session_start();
_drupal_session_write($sid, $value);
_drupal_session_read($sid);