phpnovice

I am very much new to PHP..When I tried this CODE ...till registration it is working fine. But when I moved on to login page I am getting "Couldn't Log you in. Wrong Login Information" error messsage for both correct and incorrect Login information. It means it never allows me to go to members.php. So I request you to help me with your valuable advice to go forward.When I tested without username and password I am getting the message "You need to provide a username and password." But if I am putting Correct/incorrect login i am getting same error message as I stated in Paragraph 1.