error in page loading

I encounter the following error when visiting my site:

Warning: Cannot modify header information – headers already sent by (output started at /hermes/bosweb25a/b201/ipg.bbcmarilaoorg/upstreamlife/wp-content/themes/upstreamlife2/functions.php:3) in /hermes/bosweb25a/b201/ipg.bbcmarilaoorg/upstreamlife/wp-includes/pluggable.php on line 934

Is there anyone there that can help me identify the problem>?
thanks in advance.