It's been a while since I was just starting, so I may be missing things I now take for granted, but I'll try.
The good news is you don't need to be an expert in everything. The way things change so fast it's impossible to keep up anyway, but of course the more you know the better.
I think the best place to start is to get familiar with HTML. You could start by looking at http://reference.sitepoint.com/html and other sites. And there's always right-click viewsource to see how pages have been written. The mark-up you'll find is often not best practice but it can help a lot. You don't need more than getting familiar with how it looks to start. Even this might be enough to let you start getting your hands dirty right away.
// call your function here
You don't need to upload files to your site or have a localhost server to test HTML pages, you can save a text file with the ".html" extension and it should open in your default browser.
There's a lot to web development, but having a "project" goal is a good way to learn, it helps keep focus on what you need to learn to get there.