I self-published my first two books on Amazon last fall. The only real trick is to format your document in a way that carries over correctly to the .mobi format. Basically you take your word processor file and turn it into an unfiltered HTML document, and then Amazon coverts that to .mobi. You have to get your tabs and table of contents etc. just right for them to carry over.
The Kindle Direct Publishing website gives you some guidelines for preparing your document, but not as much as you really need. I spent a lot of time websearching “publish to kindle” and reading a bunch of different people’s suggestions for formatting the document. There wasn’t any one website that had all the answers (or I’d send you there), but there are tons of them that have good explanations.
If you download Calibre e-book management, you can convert your document to .mobi and test it on your own kindle (if you have one), but that’s not really necessary, since Amazon has has a pretty sophisticated preview program that lets you see what it will look like on lots of different readers, from iPhone to PC. Also they don’t want you to upload it as a .mobi; they want unfiltered HTML that they convert themselves.
So I’d suggest first reading everything Amazon has to say on the KDP website, then searching online for other kindle authors’ recommendations for formatting, then maybe experimenting with Calibre, and then make your KDP account! Good luck with everything!