can't login to my admin form

i Tried to login to my admin page: this what i got, substr() expects parameter 2 to be long, string given in /home/palick/public_html/en/wign/conn on line 582

after enterining the user name and password then clicking on login: this what i got, Warning: Cannot modify header information - headers already sent by (output started at /home/palick/public_html/en/wign/conn:582) in /home/palick/public_html/en/wign/conn on line 93

find the code below:

line 93: function red($a) {header("location:".address."/".$a);} // Redirection

line 582: if (!substr($_SERVER['PHP_SELF'],"/admin")) {session_destroy();}

NB: i have the conn file in my cpanel as a file that is as a text file and not as a php file or html file i hope thats not a problem please i need your help.