Here’s an excellent tutorial that introduces the concept of Object Oriented Programming (OOP) in PHP. It is written lucidly but may be a little confusing if you don’t already have some basic familiarity with the PHP language.
Here’s another tutorial if you find that one a bit much.
public $prop1 = "I'm a class property!";
$obj = new MyClass;
echo $obj->prop1; // Output the property