title: Refer a friend functionality for a website in OOP
body: <p>I am trying to get to grips with OOP, and just want a little advice on how to approach a problem. </p>
  
  <p>I am making a refer a friend system on my online shop, so when a user registers they will enter an email address of a friend that referred them. This already existing friend then gets a certain amount of points (currency) in their online account.</p>
  
  <p>I have made most of my system just using functions and procedural programming in PHP, but was wondering if anyone could point me in the right direction to making the refer a friend system in OOP, or even if it is worth building in OOP?</p>
  
  <p>I do understand the basic principles of OOP, but not quite sure how to fully build a program from start to finish using it.</p>