problem installing CakePHP on Linux

Hello List I want to use Cake PHP ,I have downloaded it from it's site,rename the folder to first_app and copied it to /srv/www/htdocs my root is here: /srv/www/htdocs by entering http://localhost/first_app/ it has some errors like these outputs: Warning: _cake_core_ cache was unable to write 'default_en-us' to cache in /srv/www/htdocs/first_app/cake/libs/cache.php on line 295 Warning: _cake_core_ cache was unable to write 'default_en-us' to cache in /srv/www/htdocs/first_app/cake/libs/cache.php on line 295 Warning: /srv/www/htdocs/first_app/app/tmp/cache/persistent/ is not writable in /srv/www/htdocs/first_app/cake/libs/cache/file.php on line 299 Warning: /srv/www/htdocs/first_app/app/tmp/cache/models/ is not writable in /srv/www/htdocs/first_app/cake/libs/cache/file.php on line 299 I wanted to identify another root in default-server I used this one: <Directory "/srv/www/htdocs/first_app/app/webroot"> AllowOverride All Options FollowSymLinks # Order deny,allow # Deny from all </Directory> I restarted the apache but again the same warnings then I changed httpd.conf too. I tried hard to figure it out. if it is about the permissions I tried this one: chmod -R 0755 /srv/www/htdocs/first_app/ would you please tell me how to change the root correctly? or if it is not related to it What is the problem? Thanks in Advance.