Choose a subject you are familiar with. Parenting, gardening, car repair... all subjects people want to know about. If you are familiar with a broad subject, try to narrow it down to fit a niche audience. For example, instead of writing a basic cookbook, try "Cooking with home-grown herbs."
Keep a notebook for all your ideas. Start off by jotting down anything you can think of that would be useful in your book, making sure you list any resources you have used from books and online. If you interview other experts in the field, be sure you have their permission to quote them.
Write an outline for your how-to book. You can either write a formal outline or make a list of chapters of relevant subjects. Keep in mind that this is a book for absolute beginners in the subject. Include information that someone who has never studied this topic would need.
Begin to flesh out your chapters by thinking, "What is the most important information needed for each task?" Pay attention to details and break your instructions down into simple steps.
Type your book with a typewriter or with a word-processing program you are comfortable using. Frequently print out what you have written to look it over for errors and areas that need editing.
Decide if you want to include photographs, drawings or both in your book. If you do not have skills in these areas, find a friend or family member who is willing to help you illustrate your book for a portion of the proceeds.
Determine if you wish to edit your book on your own or hire an editor to do it for you. If you are not extremely proficient in grammar, it is highly recommended you find an editor. Even if you think you can do a good job yourself, an extra pair of eyes is always helpful to spot errors.
Check the For Dummies site to see if they already have the title you wish to have published. If they don't, you can send a list of your credentials to them along with information on the book you have created.
Self-publish your book by creating an account at a reputable print on demand site such as Lulu. As long as your book is 32 pages or longer you can download it in Microsoft Word format and offer it for sale. The site will print copies for you to order for a reasonable price.