Typesetting, or Interior Design is the formatting your book needs to go to the printer for softcover or hardcover manufacturing. Typesetting involves spacing the margins, setting the contents, indexes, sidebars, titles, and the rest of the interior layout that will make your book attractive to read.
There are several steps to proper typesetting. The first is to decide on a form factor of your book. I like the 8.5 x 5.5 for my standard non-fiction books. Check with your book printer to see the various options you have for form factors and pick one. Then, read through the style guide if they provide one. If they do not, have a look at the resources on IngramSpark; most of the printers use the same equipment so unless your printer gives you specific instructions, you can assume the style guides found on Ingram will be sufficient.
Next, decide on the fonts. Don't forget to know your font licenses! Just because a font is on your computer, that does not mean you have the right use it! If you hire out your designer (like me!) you will be confident your font has been obtained legally and is safe to use.
Once your fonts are figured out, start working on the formatting to get your pages setup for your book. The final file is generally going to be a PDF document. While word processor documents are generally accepted at many of the distribution printers, it is always safer to use a PDF file as they are designed to not change in formatting. Don't forget to embed your fonts and have proper image resolutions!
If this is all too much for you, send me a note with a little about your book and I can get you a price to typeset it for you!