HTML, Javascript and CSS are still extremely important and they have come a long way since 1990. Forget everything you knew about them and research their state in 2016. You have a lot to learn, but you'll find all three more powerful and expressive today than they were in 1990.

There is currently a big shift in the way clients want their websites to work. In the past (and present) clients were happy with simple HTML pages that were generated on the server and sent down to the client for every action the user performs. Now and in the future, we're shifting towards "Single page apps" which are Javascript centric applications that store page templates client-side and talk to the back end through APIs. Page transitions are emulated with Javascript routing libraries. This means the frontends are more complex but can provide a richer, more interactive experience. To see the cutting edge of this technique search for React + Redux.

Backend development is still important. People generally converge under a simple set of rules for backend development called Model-View-Controller. This is a design pattern that dictates how requests are delegated into your business layer. Investigate MVC as well as Domain Driven Design to get yourself up to speed.

Understand that there is an enormous amount of garbage out there right now. Some things to be extremely wary of are NoSQL databases (they have very limited use cases but are marketed as a silver bullet) and NodeJs (a backend server which executes Javascript but has more than a few shortcomings). Be extremely skeptical of any advice you receive over the internet. There are too many people dispensing advice with no actual credibility because of the ease of access to the Internet.

The best thing to do is to work with some talented developers and build your own network from them. A lot of developers on the leading edge use Twitter and often drop useful bits of advice to keep you on the right track.