PHP and Classes - OO - Accessing other classes

[markb09]

I am quite new to PHP but am making good progress.

One problem I have is understanding how to access one class from another.

As an example I have created two classes

class address{
   
    private $addressline1;
    private $addressline2;
    private $suburb;
    etc...

   function __constructor(params){
      code....;
   }

   function set_value($param){
     code...;
   }

   function get_address(){

       echo $this->addressline1."\n";

   }

} //End class Address


class person{

    private $firstname;
    private $lastname;
    private $residential_address;
    private $postal_address;
    etc...

   function __constructor(params){
      code....;
   }

   function set_value($param){
     code...;
   }

   function get_person(){
       echo $this->firstname . " " . $this->lastname."\n";
       etc....
   }

    Public function set_residential_address(address $a){
        $this->residential_address = $a;
    }


} //End class person 

When I use these two classes I am doing the following

        $mark = new person('Mark','1234556','03-Jul-1964');
    $new_address = new address('Magnolia cottage','',8,'Margaret','Street','Northmeade');
    $new_address->get_address();
    $mark->set_residential_address($new_address); 

My issue or problem is how do I display the individual address details.
What sort of class constructs do I need in the person class.

Or to display the details once I've assigned values and assigned the Person->Residential_address do I just use the
$new_address->get_address

I would think a well developed person or user class and address class would be usefel in
lots of applications.

thanks

Mark