how i can set sample data for configuration in our custom module in magento

how i can set sample data for configuration in our custom module in magento

how i can set sample data for configuration in our custom module in
magento our code is
$installer = $this;
$installer->startSetup();
$installer->setConfigData('groupname/sectionname/fieldname','Thank you for
contacting us. I\'m more than happy to assist you. You can install the
Premium Website Builder through your AMP (Account Management Panel). If
you need help please feel free to contact us. Our support department is
available to assist you 24 hours a day, 7 days a week.');
$installer->endSetup();