At first, you have to install the xdebug, for the details, you can check anthoer article:http://www.cnblogs.com/davidhhuan/archive/2011/09/28/2194851.html
sudo apt-get install graphviz
2. download the webgrind
uncompress it, and locate it to your web server,
modify the config.php
static $pythonExecutable = '/usr/bin/python';
static $dotExecutable = '/usr/local/bin/dot';
After that, you can visit http://localhost/webgrand to check the content of your website.