Error

Hi! I have this error when installing WP-PostRatings :

Warning: Cannot modify header information – headers already sent by (output started at /home6/xnelariq/public_html/wp-content/plugins/wp-postratings/wp-postratings.php:2529) in /home6/xnelariq/public_html/wp-includes/pluggable.php on line 897

I want to install because I get this and you can leave post messages:

I have this problem: Fatal error: Call to undefined function the_ratings() in /home6/xnelariq/public_html/wp-content/themes/newsworld-1.0.1/lib/hooks.php on line 512

Can you help me , please?
Thanks!
crissur