Since MySQL evidently cannot automatically insert the function now() in a datetime field in adding new records like some other databases, based on comments, I\'m explicitly tryi
You forgot to close the mysql_query command:
mysql_query("INSERT INTO users (first, last, whenadded) VALUES ('$first', '$last', now())");
mysql_query("INSERT INTO users (first, last, whenadded) VALUES ('$first', '$last', now())"
;
Note that last parentheses.