While the videos can be useful, study Shauna Kelly's page. Follow the steps there.
All of your numbered paragraphs could be based on Body Text or Normal style.

If you use the built-in heading styles, you could format them to have the same appearance as your other text or be bold, or whatever.
You just need one that is at the top level and has no numbering.
You only need the styles and levels that you will be using.