Arkadaşlar Merhabalar PHP ' De aldığım hata çok önemli lütfen yardımcı olun

Warning: mysql_real_escape_string() [function.mysql-real-escape-string]: Access denied for user 'root'@'localhost' (using password: NO) in /opt/lampp/htdocs/GirisYap.PHP on line 6

Warning: mysql_real_escape_string() [function.mysql-real-escape-string]: A link to the server could not be established in /opt/lampp/htdocs/GirisYap.PHP on line 6

Warning: Cannot modify header information - headers already sent by (output started at /opt/lampp/htdocs/GirisYap.PHP:6) in /opt/lampp/htdocs/GirisYap.PHP on line 45