Hmm, there is a lot to self publishing, enough that I also plan on writing a book on that down the line. Without getting into all the different nuances, here are the easiest steps to take.
Write the book on Word. I gave up Microsoft Office and will be experimenting after my move with Open Office, but I am not sure it will be compatible.
You can either design your own cover, using a picture that you would purchase from a site like DepositPhotos. I am not a wizard with programs like Photoshop, so I used an online site (free) to make many of mine https://www.canva.com/
You can also use talented designers for the cover on Fiverr for cheap, but make sure to provide your own picture as many of them use stolen pictures without permission.
Once you have the book written, put your table of contents in the front (Word compiles it from the headings) and you are ready. The easiest way to now get it uploaded and published would be to upload it to https://draft2digital.com/
They are an aggregator who will then get your book(s) on the various online book stores (Kindle, Nook, Apple, Kobo, etc). You can set your price. Now a word of caution here. To make the book free you will not want to pick for them to send it to Amazon. Amazon is a pain, and really tries to dictate how the market runs as they come closer to being the only platform daily. If you upload to them through D2D (or directly to Amazon) they frown on your book being free, disallowing it completely through the likes of D2D. It is a hassle even going direct and I advise against the hoops.
Then you can also upload it to sites like https://bookfunnel.com/
They might charge a little, but I can tell you people do use it effectively as a funnel in collecting email addresses.
It has been awhile since I have self published, but there are marketing companies you can use to promote that will result in a good number of people downloading the book. The best and most affordable for this type of book would be https://www.freebooksy.com/for-the-authors/
If you run into any difficulties just give me a shout. I don't do the discord thing, but you can ask on this old post of mine as it seems someone else was directed to it to ask me questions recently regarding self publishing. That way it doesn't disrupt anyone elses posts.
https://steemit.com/howto/@practicalthought/self-publishing-for-a-residual-income
I will look further into this, very interested. Thank you!