Sorry, you do not want to pay my hourly rate to do this! My function here is to teach you to fish, not to serve dinner.

You do not have automatic numbering attached to your headings. If you did, this would be very simple. Refer to the article by Shauna Kelly on how to do automatic numbering. It is a step-by-step process. Do this with a copy of your document until you are confident it is doing what you want.

I noticed a number of things that could cause problems in your document, long term, including the use of the Enter key for spacing. I would urge you to take the time to read the series of pages beginning with: Basic Concepts of Microsoft Word - from Shauna Kelly. It will save you time and angst in the long run.