Error Warning: Cannot modify header information

i am getting this error plz solved it help me to sort out ..

i only wana do to hide my post from front of my homepage there are many pics to show .. i found this topic and i do

http://wordpress.org/support/topic/257866?replies=8

after that i got this error but no any can help me to sort out what i do ?

Warning: Cannot modify header information – headers already sent by (output started at /home/careersi/public_html/wp-content/themes/tigopedia-reloaded/functions.php:25) in /home/careersi/public_html/wp-includes/pluggable.php on line 868