Your website will be the place the majority of people go to find your book. Make it reflect something about you. Put as little or as much as you want out there, but at a minimum you need a page about yourself and one about your book and how to buy it. Buying your book has to be the easiest thing for anyone visiting your site to do. Put “buy” links on as many pages and in as many places as you can.
My website is fairly static, I update it only when I feel I have something to add. Spend some time looking at websites of your favourite authors (famous and unknown) and see what they do. Think about what you want. Then get a site.
There are free web hosting sites out there, you can do an internet search to find them. I’m lucky in that I have a nephew who actually creates websites for a living, so he gave me a head start. But I’ve developed most of my website myself. Regardless of who sets up your site, you need to be pretty hands on so you can change it and improve it as you go. This page, for example, is something that I decided to do long after my first website was put up.
Once you have your website, add your url in your signature wherever you use it online. I have my website at the bottom of every email I send and I include it in most posts, I place it on chat groups or blog comments. You never know when someone will pop over to your website for a look-see.