Strange error after uploading

Hello!

I downloaded Piwik and uploaded it on my Server. After that i navigated to the index.php for installing but then came this error:

Fatal error: Uncaught exception ‘Zend_Session_Exception’ with message ‘Zend_Session::start() - session_start() [function.session-start]: open(/var/lib/php/session/sess_34nj4m4dvln258pohiu5cqqs83, O_RDWR) failed: Permission denied (13)’ in /var/www/html/web74/html/piwik/libs/Zend/Session.php:379 Stack trace: #0 /var/www/html/web74/html/piwik/index.php(50): Zend_Session::start() #1 {main} thrown in /var/www/html/web74/html/piwik/libs/Zend/Session.php on line 379

Maybe you can tell me whats wrong.

Your web server doesn’t have permission to write to that folder.

If you’re the sysadmin, chmod/chgrp as needed.
Otherwise set the session.save_path in your local php.ini, .htaccess, or bootstrap.php.

[quote=vipsoft @ Sep 20 2009, 03:31 PM]Your web server doesn’t have permission to write to that folder.

If you’re the sysadmin, chmod/chgrp as needed.
Otherwise set the session.save_path in your local php.ini, .htaccess, or bootstrap.php.[/quote]
sorry, i am very poor at this stuff. which chmod-code is needed? i tried 777 but it didnt work, there comes an internal server error