I am working on a document which comes in a template format for my company. The document has a table of contents which I need to edit and amend. But I cannot get the table to display the added headings which I have added in the body of the text. I don't know how to do this.

It seems MS Word will not reconcile the old headings found in the table of contents with the new headings I've added in the body of the text. It won't simply add them. How do I add new items in the table of contents?