slider

i tried to create the slide by putting the homepage slider box but when i publish it displays the below error message. please help!
Warning: Cannot modify header information – headers already sent by (output started at C:\xampp\htdocs\wordpress\wp-content\themes\appointment\functions.php:59) in C:\xampp\htdocs\try392\wp-admin\post.php on line 235

Warning: Cannot modify header information – headers already sent by (output started at C:\xampp\htdocs\wordpress\wp-content\themes\appointment\functions.php:59) in C:\xampp\htdocs\try392\wp-includes\pluggable.php on line 1121