I get really desperate right here. To be able to constitute some Search engine optimization I wish to redirect my none-www into www site. Obviously simple 301 redirect ill d the secret, and in addition it work.

BUT

What does not work, whatsoever, is really a wordpress. I've my very own VPS, and i'm setting up wordpress by application manager in plesk panel. But when i activate the htaccess file, wordpress can't be installed any longer (oddly enough it informs me that mysql extension isn't triggered) and existing wordpress pages stop orking with infinite loop error. After I remove htaccess everything works fine.

Please if anyine has idea how do i redirect and also have wordpress in the same, it might me much appreciated

Bypass the issue. Setup an easy example.com domain/site in Apache, and pressure it to without any reason redirct to www.example.com. Wordpress would simply be mixed up in www.example.com site's setup, and example.com is available Simply to redirect towards the www version.

This way you are not looking to get your .htaccess stuff to exist together with Wordpress', and also the redirection happens far outdoors of Wordpress' domain.