You should now begin to write the contents of the various sub topics you listed earlier one by one. Remember that these are the chapters of your book. Since you are an expert, you should have a lot to write here.
Steps to Write These Sub Topics:
Write out the sub topic on a plain sheet of paper. For example, How to Get Trained as a Newspaper Publisher.
Take this sheet of paper with you everywhere you go and roll over the subtopic in your mind all through the day. If you can find a quiet place during the day, you should be able to put down ideas as they flow through your mind. Even if you can't find a quiet place, ideas can still flow through your mind at any time during the day.
You should ensure you write them down immediately on paper under the written subtopic. It is like you are developing the subtopic as a book itself. Subtopics or chapter contents are books under a book themselves.
When you get home and alone you can look at what you have written down under the subtopic. For example under the subtopic above, I can have
Can you get the gist?
You should now begin to develop these points one by one. You can write one at a time when your mind and thoughts are in a good condition to put facts on paper. I love to carry out this step in the morning before 12 pm or in the middle of the night or in a place where there is less noise. You should find out the best time that is okay with you.
Write Freely.
There is nothing to be scared of. It's easy, remember that you are an expert. The editor with the help of other tools will polish your book and make it a treasure the people will love. You should just ensure the contents you are putting down actually solve the problem your book is solving. Of what use is a properly written book if it is not solving the problem it is meant to solve?
Do the same to develop other subtopics of the book.
"Marry" Your Points.
When you have finished the step above, you should now go over your work from the introduction to the last chapter to bring the contents together. I call it; 'Marry' your points.
At this stage, you may find out you have unnecessarily repeated the same idea twice or thrice under the same chapter. You may even find out some points that are completely irrelevant which you have to delete.
If you carry out this step, you will be able to do a lot of refining to your book contents before you send it to the editor. I usually carry out this "marrying" duty twice (and sometimes thrice) on some of my books before it is sent to the editor.
Get it typed, print and read through again. You may still need to delete or add some points.
Write the Conclusion.
This is usually not a big deal except for the fact that you have to say thank you to your readers for reading your book. You can also ask them to contact you if they have any comment or suggestion for your book.
You will be surprised to see the number of people that will send their comments to you. Some will even go to your blog or website to give their comments. These comments can really help you to write an improved version of your book or to write a new book.