default.css or 1.css will sit in root where all site files sit, public_html/
you should NOT need the sql but here is sql to instert stylesheets.
Code:
INSERT INTO `stylesheets` VALUES (1, '1.css', '(default)');
INSERT INTO `stylesheets` VALUES (2, '2.css', 'Large text');
INSERT INTO `stylesheets` VALUES (3, 'name_of_stylesheet.css', 'Style_Name_Here');
and images should go into pic/