query in mysql but i need some help

CREATE PROCEDURE InsertName
(
`username` VARCHAR(300),
`password` VARCHAR(300)
)
AS
IF EXISTS (SELECT id FROM users WHERE `username` =`username` AND `password`=`password`)
ELSE 
BEGIN  
 INSERT INTO users
(
   `firstname`,`lastname`,`email`,`contact`,`username`,`password`,`sec_question`,`sec_answer`
)
VALUES
(
  `firstname`=`firstname`,`lastname`=`lastname`,`email`=`email`,`contact`=`contact`,`username`=`username`,`password`=`password`,
`sec_question`=`sec_question`,`sec_answer`=`sec_answer`
);
END;