Changing Language

Hey, well I installed sucesfully WordPress then I wanted to change language to Spanish. So I downloaded the es_ES.mo file and created the language folder in wp-includes and put it there, then modified the config.php file, everything according to the instructions with no problem at all BUT when I tried to access the admin page this appear on the top of the login console:

“Warning: Cannot modify header information – headers already sent by (output started at /home/federaci/public_html/Protesis/wp-config.php:24) in /home/federaci/public_html/Protesis/wp-admin/admin.php on line 10

Warning: Cannot modify header information – headers already sent by (output started at /home/federaci/public_html/Protesis/wp-config.php:24) in /home/federaci/public_html/Protesis/wp-admin/admin.php on line 11

Warning: Cannot modify header information – headers already sent by (output started at /home/federaci/public_html/Protesis/wp-config.php:24) in /home/federaci/public_html/Protesis/wp-admin/admin.php on line 12

Warning: Cannot modify header information – headers already sent by (output started at /home/federaci/public_html/Protesis/wp-config.php:24) in /home/federaci/public_html/Protesis/wp-admin/admin.php on line 13″

I logged in and everything was still on english and that Warning lines continued on the top of the dashboard. Am i missing some step or did I screw it up somwhere? :p

Thanks in advance