Self publishing has many advantages and a good few problems. Let's look at the tools I use to get my books published and a word of caution on how much money you are going to make;

1. If you just want to create a book to promote you and your goal is not big sales, you may decide to make it a free offering to showcase yourself as the expert. If this is for you, you don't need a lot of expensive kit to create something functional that will do the job.The below book was created on Publisher. Saved as a PDF. The design was created (rightly or wrongly) on Canva and the 3D image of the book was created with DIY Book Covers It then sits on the homepage of my site and on my book page. And obviously features in my marketing, speaking engagements and is offered for free to clients and people who are struggling with the Imposter Syndrome.
2. Amazon self publishing option guides you through it. You will need to create a PDF of your manuscript and a book cover. There are book cover designs on this platform to use if you feel that creating your own cover is outside your area of expertise or if you are not going to employ a graphic designer to design this for you. There is also further advice, guidance and tools to make your book look good. In my view the quality of the books has deteriorated recently. I'm hoping it is just an issue caused by the Pandemic although I will be monitoring this. Because I write so much I'm often contacted by companies that would like to work with me in a similar way to Amazon's self publishing option. I will let you know if I move to one of these in the future. (On the Insiders). Working with Amazon means your book is on their platform. The costs to print are low because it's on demand printing and you aren't stuck with hundreds of books to store and ship. (They do all that for you too!) To be fair there is little I don't like about it!
3. There is a lot to consider for self publication. There are companies that are well established who just help you work out which category to put your book in! Since that can be the difference between being a No.1 book or a 1,0000,000 book. (As a rule the smaller the category the more chance you have of featuring as a best selling author because you won't need to sell 20,000 books to get a top 10 listing.) This will be essential to learn if you are writing a book to make a lot of money. Please note few people make a fortune from writing books. I can say I've made well over £14,000 from book sales which is really good but it's not the goal for me. The goal is to open doors to big ticket events and corporate clients. And it works. It's a nice cherry on the cake that I make money with this form of marketing!

You will need to be creative and open to new ideas to be able to sell your book on either path you choose - self publication or traditional publishers.