If you plan to be a professional writer you need a web site. It's an important tool to communicate with your fans. At the very least it should have a list of your books and where readers can get them, a brief bio, and possibly a little bit about the backgrounds and people portrayed in the books. You should avoid, however, going into too much detail about the plots, to save yourself from accidentally or otherwise giving spoilers.
A published author with a track record can get away with talking about works soon to be on bookshelves, but even they should avoid talking about works in progress. You need your info to be timely, or else you will disappoint your fans. An unpublished author should avoid talking about their works, for your readers will soon become impatient at their inability to get anything. Forget about drumming up business before you have business to sell. That's an opium pipe dream that too many beginning writers fool themselves into believing.
You can, however, begin to establish yourself and build up your social network. Blog (briefly!) about a few topics interesting to you. Those will show up in your books even if you don't deliberately add them, and your likely fans will also be interested in those topics and your books.
On my site, for instance, almost every week I post something about new technical developments, especially in aerospace, and especially in military fields. I'm an expert on those areas having done classified and unclassified work in them for many years and like to ferret out interesting new developments.
I also post almost every week about interesting new developments in sci-fi/fantasy books and movies and TV shows. Occasionally I post about quirkier matters I've come across.
I always end the (short!) blog post with a colorful and fascinating visual, usually a book cover or photograph or a YouTube video.
An unpublished author is in a good position. You can make your mistakes before many people know you. Here's advice that comes from many experienced web site creators, not just from me.
- Start with a free site so you won't spend money on a trial effort.
- Start small.
- Take baby steps to improve and add to your site.
- Stay as small as you can. In other words, avoid a kitchen-sink approach, avoid clutter, avoid complicated search paths through your site. SIMPLE most often equals ELEGANT.
Finally, use WordPress.com. It's the most easy-to-use host platform with lots of options to customize to it to YOUR unique vision. There are other practical and technical reasons for this choice, too. Here is WP's propaganda about their advantages; I've found it to be truthful, not hype.
https://en.wordpress.com/features/