This is a formatting/styles issue, where the Table of Contents is not picking up all of the headings you require.
You will need to go to a heading that the Table of Contents currently does include, using the Paste Format tool, first click and select the whole paragraph of the heading that is working in the contents. Double click on the Paste Format tool (so that it stays on to apply the correct format to one para after the other - ensure you click in the margin and drag over the entire paragraph of the Heading).
Updating the table of contents is as simple as placing your cursor within the table of contents and pressing F9 - entire contents.
If your table of contents is not picking up all of the different levels that you require, you will need to select all of your table of contents, Insert -> Table of Contents
-> Options. Check that the headings you need have a heading level number against them -> OK -> OK (Update).
-> (tick) Use hyperlinks as page numbers.
You should now see an updated table of contents.
Remember you can always go back and try again. It's the way to learn and understand how things work. =.- ))