Step 1: Platform Compatability
Step 2: Setting up your server
Open a terminal and type:
sudo apt-get install php5 mysql-server apache2
It will prompt you for a root MySQL password, so give it one.
Open a browser and go to http://localhost. You should see a page that says "It works!". Next run this in a terminal:
sudo gedit /var/www/info.php
And paste in this code:
Save and close the file, then run
sudo service apache2 restart
Go to http://localhost/info.php
and you should see a purple table with a bunch of PHP stuff. If you do, congrats! You are now running a PHP server. Next, let's set up a page to control the Arduino.