How To Publish An Ebook thang.)
I'm only telling you what I do. If you prefer to publish on the Nook or through the iBookstore, write a howto for that step, let me know, and I'll link to it. If you prefer to publish on Smashwords, nag me and I'll write that up, too.
Getting an account on Kindle Direct Publishing (KDP) is pretty simple. You will need to know a few things before you start, or be ready to do some scurrying to get the info at the last minute. Since Amazon will be sending money your way, you need to give them a tax ID number. So, have your Social Security Number available. (If Social Security is an entitlement, why is your SSN a Tax ID?) You'll also need to give Amazon a place to send your money. So, have your bank account's routing number.
If you're smarter than I am, you've established a budget for your ebook publishing venture. If you haven't established a budget, stop right now and plan one.
When you create the ebook account, just put that much money into this bank account plus some margin as working capital. If the account has a minimum balance, make that or 15% (whichever's larger) the extra margin amount.
When you've got everything set up with KDP, you'll be able to publish your ebook. If you've already made your ebook's MOBI file and have put all their metadata in exactly the way you want, you're ready for the next step.
Otherwise, get to work with Sigil, Calibre, etc. and your ebook perfect.
You did proof it and run it past a dozen beta-readers, didn't you?
Here's another thing I didn't warn you about: You have to hire an editor. You need someone who isn't you to scour the ebook looking for typos, grammatical errors, spelling mistakes, and stupid stuff. The main thing that makes self-published books suck is the failure to take this step.
In that case, find another impoverished ebook writer, or the most pro-active of your beta-readers, and set up a barter arrangement. "You edit my book, and I'll edit yours... Or paint your bike shed. Or something..."
Just Make Sure Your Book Is As Close To Flawless As You Can Make It.
(You can find the bullet-point outline of How To Publish An Ebook here.)