Are you sitting down? You have to be sitting down to write a novel so that's step 1. Step 2—the blank page is waiting. Start filling it up. HOWEVER, if you think, "OMG, I've got to write hundreds of pages and how will I ever, ever do that when I've got nothing but...almost nothing...maybe a tiny idea, maybe a vague character? This is impossible." If you think this or something like this, it might be impossible. Think smaller steps... Whether you begin with an outline or you just start writing, don't focus on writing a novel. Don't even focus on writing a chapter because what a chapter is, that's vague. What you want is a step that you can easily climb up. What you need is a clear goal. THINK scene. Think of a scene you want to write. My advice is even if you're not an outliner, you write a little one paragraph note to yourself about what happens in this scene you're going to write and what you want the reader to feel or maybe think and what happens and something about the people involved in the scene. Then write that one scene as best you can. Then go on to the next scene. Often a scene will be a chapter but not always. That doesn't matter. Just keep moving from scene to scene. My advice is that you keep trying to give yourself a foot up in the scene by writing a quick paragraph about each scene before you write it. Then write the scene. Then move on to the next.
Step by step, scene by scene, you'll reach where you want to go which is that final page with that final sentence and the words THE END.