2
it will vary depending on the module.
basically you should edit the code, and move the line that says $xoopsOption['template_main'] = 'module_template.html'; above the line that says include XOOPS_ROOT_PATH . '/header.php';
ie.
$xoopsOption['template_main'] = 'your_module_template.html';
include XOOPS_ROOT_PATH . '/header.php';