Heading styles can be found under "Styles" in the Home tab.Once you have applied the heading styles to any headings you wish to have appear in the TOC, your hard work is done!In theory, the Table of Contents should update automatically as you work on your document. Here are a few problematic situations you might run into, and their solutions.
Any heading that you wish to have appear in your TOC will need to have a specific heading style applied to it, Heading 1, Heading 2 or Heading 3.
In this case, try using the F9 key to update the document fields.
If the problem occurs when you print the document, check your print options. Open the Print tab and then select Update fields in the Print Options section. If you need to add something to the TOC manually you can do so by going to the References tab, and then clicking on the Update Table in the Table of Contents group.
Now, just put your cursor where you want the TOC to appear and go to the References tab.
Next click Table of Contents and then select either Automatic Table 1 or Automatic Table 2.
Another option is to go to Outline view and click Update Table of Contents on the Outlining toolbar.