1. Like with any project, research is key to find out what topics are selling the best. The New York Times Best Sellers list (http://www.nytimes.com/best-sellers-books) and Amazon.com are great places to start. Jot down the catagory the best seller is selling in.
2. For whatever topic you choose, use and check your facts. I use Wikipedia.
3. Everybody writes differently. While some can write in order from head to page, I usually tend to develop an outline.
4. Begin writing your book. For a simple one day ebook, you will want to shoot for at least 20 pages but no more than 30 pages.
5. After you have finished your masterpiece, have someone read over the book and do spelling and grammer checking.
6. Now you get to create a cover. I like to use GIMP Image Manipulator. Amazon Kindle likes ebook covers that are at least 1600 x 2044 px in size. You can make an easy cover by downloading an image that best suits your books subject and writing text over the photograph. Then you'll want to save it in .JPEG or .PNG.
7. Now you will want to write a summary for your ebook, choose tags (when choosing tags, pick some that are similar or the same as your best selling counterpart), and pick the ultimate selling catagory. (see step 1)
8. Now it is time to upload the book and the cover to Amazon Kindle (https://kdp.amazon.com/) and answer a few questions and set the price and in which countries you want your book sold. You will want to choose a price. I suggest $0.99 up to $1.09.
9. Now, use social media to push your book.
Note: Typically, Amazon Kindle will tell you that it takes between 1 - 2 days for your book to be published, but normally it only takes a few hours. If your book is based, or is an open source or public domain book or information, it will be rejected.
Now go write some money into your pockets!