There is a very clearly defined novel writing process. These components of the writing process can be followed, step-by-step, to get you from the first twinges of the desire to write right through to that wonderful moment of holding your first novel in your hands.
The first thing you need to do is to ask yourself if you have what it takes for a creative writing career.
Then, before starting to write your first novel, educate yourself in the art of creative writing. You don't need to get a formal education in it (although you can, by all means, if you like). But learn all you can about creative writing, including the information on this website. There are lots of excellent videos at Writer's Digest Tutorials for example.
Then decide what genre you might like to write in. This will most likely be the genre you spend most of your time reading.
The next thing is to decide on your plot and your characters. These two steps are intertwined to a large extent. Some writers prefer to start with the plot, others with the character, so you'll need to find out which one suits you better.
The next step is to do any research you might need to do. You mightn't need to do a whole lot to start with, though. And don't use research as an excuse to put off writing! Research tends to be an as-needed thing in my experience, and will continue during the novel writing process as you realise the gaps in your knowledge.
Once you're finished the first draft, go into the revision and editing part of the novel writing process. Once the novel is as perfect as you can make it, you then go about getting it published. And at the same time as you're pursuing getting your first novel published, you start writing your second novel. This is very important.
Either your first novel will find a publisher, in which case they'll want more work from you - and under a deadline too. (The first novel is the only one where you have the luxury of writing it at your leisure).
Or, your first novel will not find a publisher. It was your learning/training novel - and your second novel may well be the one which finds a home.
Either way, you need that second novel, and writing it helps stop you fret over the fate of the first one (to some extent at least!)