having trouble with www folder and localhost???

this may be because your /www folder located in the /var folder and chmod is lower than 755
open the terminal and type
sudo chmod -R 777 /var/www
or for specified folder in /www type
sudo chmod -R 777 /var/www/foldername
it will give full access to the files in the www and subfolders... so if u use joomla, wp, drupal after installing components plugins for these cms`es take this action to get full access....