Proofread your manuscript for grammar, structure, and content. Remember to run spell check. You may want to have friends and family read it to catch anything you may have missed.
Go to Lulu.com and CreateSpace.com and read about what they have to offer. With CreateSpace, your book will be available through Amazon if you have them assign an ISBN. With Lulu, your book will be available through the Lulu Marketplace. You can even create your book on both sites if you want. Make an account with the site you wish to use. Keep in mind that you cannot create hardbacks with CreateSpace.
Create a new project and upload your manuscript.
Create your book cover. These two sites have cover-creating software that can help you. You can choose from already made templates or you can choose a template that lets you upload your own cover artwork. If you are uploading your own cover artwork, make sure that it meets that site's guidelines, or else your book cover may not have the image definition you desire.
Set the price. You cannot set the price lower than the cost of actual printing. The websites will give you a price based on the specifications you chose for your book and the book's length.
You can now buy your book at a discounted price because you are the author, but other people will have to buy it through the sites you used at the price you set for your book. You can have any number of books shipped to you or another address at the at-cost price, and you will also have to pay shipping.