自动更新产品版本？ - PHP

I created a product using php that I want to put on a website, but before I can do that I have to get it to update automatically. For example I have version 1.0 and there is a new version 1.2 it has to automatically ask the user to update and update if he/she has chosen to. I have part of the code to show the newest version:I created a product using php that I want to pu