So i've kind of fallen into web design.....

Been doing a couple of small basic sites here and there, mostly just HTML and styled with CSS, but more recently done a couple of OpenCart webshops and Wordpress sites in PHP and need to know what to do for taking it to the next level.

I've done everything so far using Notepad++ and a Synology server running Apache/PHP but find it cumbersome now i'm getting into manipulating the backend.

So what do I need to know about IDE's - where to start... ?