There are a lot of guides out there for how to write, publish or self-publish a book.
I can't comment on traditional publishing. I didn't self-publish because of rejection from traditional publishers; I never submitted a manuscript to a traditional publisher for consideration. I read numerous guides comparing the two and decided self-publishing would be better for me in the long-run.
The best place I found for resources on self-publishing is Reedsy. It helped me to no-end. I cannot stress how amazing and fantastic of a website it is, and anyone looking to find out more about becoming an author should definitely check it out. It also has free courses with several lessons, each delivered once a day which I imagine are also great, although I just scoured the blogs because... impatience. There are also blogs on writing tips, including cover and plot design, blurb and bio writing, and character development.
For information on the specific approach that I took to self-publishing once I'd accumulated enough knowledge to have a go, I may write it in a blog post at some point in the future. As I write this, though, I'm actually still in the process of finalising my first book's cover, getting it set out for initial reviews, and then putting it up for pre-order while I focus on marketing.
Everyone looking to promote something needs a website in today's world. Building a website can be a lengthy, troublesome process, but it doesn't need to be. The internet is full of helpful tools to help you get the job done quickly and efficiently. One stands out in stark contrast by its sheer volume and attention to detail, clearly conveying the passion of the content's creators for both building websites and helping others achieve their goals.
Whether you're uncertain or confident but curious, you can arm yourself with all the information you'll need from this well written, very comprehensive and detailed guide to making a website in 2020. This boon for the new website creator will walk you through making your new website or blog, step-by-step. Those who are technologically savvy will be able to find more technical guides, as well as outstanding reviews comparing the advantages and disadvantages of different platforms, allowing you can go in with your eyes wide open, instead of narrow and sleepy after spending hours hunting for less objectively composed information scattered across the web!
For readers/fantasy writers
I wish I'd thought to save resource links as I went, but sadly, I didn't. I'll endeavour to change that, going forward.
Here's a great one for Norse Mythology: https://norse-mythology.org/