In your includes/languages/english/mysite/ meta-tags.php file find the KEYWORDS areas and enter a comma seperated list of keywords for your site - Your description is different but I think you have that already
Code:
// Custom Keywords
define('CUSTOM_KEYWORDS', 'model cars, model airplanes');
// Home Page Only:
define('HOME_PAGE_META_DESCRIPTION', 'MODELING REMOTE CONTROL SLOT CAR ROCKETS PAINTBALL GIFTS AND TOYS model cars, model airplanes');
define('HOME_PAGE_META_KEYWORDS', 'model cars, model airplanes, hobby center, hobby supply, rc car, rc boat, rc heli, hobby store, hobby stores, hobby shop, rc helicopters, rc planes, rc airplane, hobby supplies, rc boats, rc hobby, rc airplanes, rc helicopter, rc plane, r/c, rc, mail order');