every time i open my yahoo account it is full of messages from orkut!!!!
Please tell me how to stop them i know that i'll have to change some settings in my orkut account but i don't know which settings please help if you know something about it.

That is quite easy .

Login to your orkut account..
Goto ---> Settings ---> Notifications ---> Now uncheck all email notifications
But mostly it is scraps who anny most so for that you can simply turn of email notification for "new scrapbook notifications" .