Your idea is the first thing you need to start creating. There are all kinds of different websites you could create, but it is reccomended that you start with something simple for your first website. Whether it be a simple personal website for just you to try it out, or some kind of informational piece, there are tons of ideas out there.
When you first begin brainstorming, try to come up with something that sounds easy, avoiding anything too complicated. Try drawing or writing down your idea(s) on a piece of paper to keep a note of what you want to make.
Cant think of anything?