[20years]

Being that you are already familiar with HTML/CSS and PHP, I suggest getting updated with those first. Learn responsive design or Bootstrap to get started on the front-end (HTML). Do some reading on the latest CSS best practices and go through a couple of JavaScript and jQuery tutorials. For PHP, I suggest reading through http://www.phptherightway.com/ because a lot has changed with PHP over the last few years.

All of this will give you what you need to built out a robust site. After you are updated and comfortable with these, you may then decide to move onto learning other things such as React, Node, etc.