J1.5:How to create a custom button
From Joomla! Documentation
The scripts below are used for using the backend toolbar when developing components or modules.
Put this script on your component for a custom button:
JToolBarHelper::custom($task = , $icon = , $iconOver = , $alt = , $listSelect = true, $x = false);
For a back button you can use this one:
JToolBarHelper::back();
Calcel button:
JToolBarHelper::cancel();
Apply button:
JToolBarHelper::apply();