There’s still lots of demand for competent IT people, and they pay very well still. It’s just a bit harder to find them in today and tomorrow’s economy.
As for which one, I would say it depends on your skill. Network admins tend to know hardware and Linux/Unix/Windows server. Teamwork is less important here, if you know your stuff you can often run solo, sometimes in smaller companies you may BE solo anyway. Web and app programmers tend to know programming logic, at least one language inside and out though preferably more, know the principles of quality code, can work in a team if needed or at least communicate well with other people. The only difference between web and app programmers is the languages and data storage options, as we go on more apps are being a fusion or developed in a traditional code environment but are actually web apps too, the differences are blending together.
I often find that while someone can be strong in all areas of computing, one tends lean in the direction of hardware and mucking with cables and many computers, or software and mucking with code on one computer.
Don’t worry about schooling now, while I am formally educated in these fields, I was very competent before than because of mucking around on my own. There are lots of tutorials for every language, and you can even host a server on your own computer for local testing so as to learn PHP/MySQL. Good luck :)