我一直在安装apache 2和php5，我知道这是index.php文件在var/www/html/index.php，但我想把它改为/home/pc/www/public/index. php和我安装在etc/apache 2/sites-available/000-default.conf文件根“DocumentRoot /home/pc/www/public/”这里是我的conf文件：

<VirtualHost *:80>
    # The ServerName directive sets the request scheme, hostname and port that
    # the server uses to identify itself. This is used when creating
    # redirection URLs. In the context of virtual hosts, the ServerName
    # specifies what hostname must appear in the request's Host: header to
    # match this virtual host. For the default virtual host (this file) this
    # value is not decisive as it is used as a last resort host regardless.
    # However, you must set it for any further virtual host explicitly.
    #ServerName www.example.com
    ServerAdmin webmaster@localhost
    DocumentRoot /home/pc/www/public/
    # Available loglevels: trace8, ..., trace1, debug, info, notice, warn,
    # error, crit, alert, emerg.
    # It is also possible to configure the loglevel for particular
    # modules, e.g.
    #LogLevel info ssl:warn
    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined
    # For most configuration files from conf-available/, which are
    # enabled or disabled at a global level, it is possible to
    # include a line for only one particular virtual host. For example the
    # following line enables the CGI configuration for this host only
    # after it has been globally disabled with "a2disconf".
    #Include conf-available/serve-cgi-bin.conf
</VirtualHost>
# vim: syntax=apache ts=4 sw=4 sts=4 sr noet

当我尝试在Firefox中访问localhost时，我得到了这个错误：

Forbidden
You don't have permission to access / on this server.
Apache/2.4.7 (Ubuntu) Server at localhost Port 80

但是当我设置DocumentRoot为默认目录时，它可以工作。请帮帮我