Ok, this may be a pet-peev of mine but lets make sure you are trying to become what you think you are trying to become so you don't waste your time going down the wrong path.
Web-Designer: Someone who designs web pages? Most people believe that anyone who creates a web page is a web designer. This is not so. I am not a web designer I am a Programmer (or web application developer if you prefer). A web designers job is to make a web page look good, and be easy to use (User Interface stuff). If you want to be a web designer you need to concentrate on HTML and how HTML renders in all of the different browsers, and how graphics look, and what fonts are best for the type of page you are building. A web designer doesn't need to know anything about the "code" that is behind that page, only the display of the information.
Programmer (web applications developer): This is the person who sits behind the scenes and makes sure that the proper data is fed to the proper places. A programmer built the Phourm system that is this message board, not a web designer. Programmers are focused on building a set of tools that will take data in one form and make it useful in another form. Programmers usually don't care what the program looks like as long as it does it's job. Programers are the ones who need to know PHP, Perl, Java, CGI, C, C++ and any other language that comes along that will let them do there jobs. Most Programmers don't even need to know HTML beyond the basics.
So do yourself a favor and research the two before you run off to become either. Most Web-Designers that I know come from a graphic design background, and are fairly good artists. Most Programmers that I know couldn't draw a squiggly line to save their lives (myself included).
Once you've figured out which path you want to follow pick the main tool that you will need to learn and learn it first. After you have mastered that then pick up the others. Just remember that the Web is a dynamic place and what is king today may not be tomorrow.