iam getting the error

hi,

iam new to php,I created one login page,it is giving error is that headers already sent,please help me how to remove that error.

"Warning: Cannot modify header information - headers already sent by (output started at C:\wamp\www\testproject\login.php:1) ",iam getting this error.

thanking you,

Quit trying to send a second header and that message will stop occuring.