> I taught myself PHP
That's awesome. I respect anyone who has the desire to learn, the puts in the work, and has the discipline to see it through.
PHP is of course a language, a set of vocabulary. At the back of any textbook, you'll find a glossary, the language or vocabulary used in the book. You've already learned the language, the glossary, of PHP programming. If you look, you may find there's a lot of cool stuff in the other parts of the book, systems architecture stuff, software engineering, analysis of algorithms, etc.
You need to learn a programming language or two before you learn analysis of algorithms or software engineering, because the languages are the vocabulary words of the field.
To give a concrete example, when I started my current job, the company had a software system that worked - mostly. A team programmers had worked several years on it, and all knew the language they were working in. Customers just wanted it to be faster. It was definitely too slow. Although it was my first month on the job, when I heard the complaints of slowness I said in a meeting "I'd like to take a look at that; I can probably make it 20%-30% faster easily enough for now, then do more after I understand how it all works." The team was rather skeptical, in fact they chuckled out loud at my claim, saying "I rather doubt you can do that". "How long do you think that'll take?", they asked. "Give me a week", I said, though I hadn't yet seen the code. They laughed again, hundreds of thousands of lines of code and this new guy was going to make it 20%-40% faster in a WEEK? Doubtful, they said. To put me in my place, they said "sure, go ahead and try that [wiseguy]."
As I left the meeting I realized I had just taken a big risk. When I went home I told my wife that I had just bet my reputation at the new job on a claim I only hoped I could fulfill. If I failed, it would establish that I'm an arrogant prick. If I succeeded, I'd be known as possibly the best programmer in the building.
Well a week later I had it running 30% faster. Why could I, in a week, make drastic improvements to code they'd been trying to speed up for months and years, code I'd never even seen before? They all knew the language almost as good as I did. But I had been taught to study much more than the language. They knew C, Perl, and Erlang; I knew algorithms and cache theory. So in a week I did in fact make major improvements to their years of work.
Now, I'm going to go upstairs and check the progress of my benchmark. Now six months into the job, a major customer again complained about slowness, so I've been looking at that for a few days. I hope to see that my three day's work has made the system another 20% faster. I'm a tad nervous because I need to impress the new boss, I think that by learning more than just the language (glossary terms) I'll be able to do that.