A family of Microsoft word processing software products for creating web, email, and print documents.
That is not how to create a Table of Contents, or add entries to one.
The issue with your 'new entry' may be nothing more than your failure to refresh the Table of Contents, which you can do by selecting it and pressing F9. If that isn't sufficient to add the new entry to the Table of Contents, the implication is that your new entry hasn't been formatted using one of the Styles the Table of Contents is pulling data from. Apply such a Style to the new entry, then re-select the Table of Contents and press F9.