Here is a list of the authorities you can cite in Word's Table of Authorities:
This is the order which authorities will be organized in your Table of Authorities. Cases will go in Section 1, statutes will go in Section 2, etc.
Marking the First Instance of a Citation
You will get a dialog box that looks like this:
Next, you will decide on what category you should place them in. Make sure to select the correct category and click OK. (If the citation you're marking doesn't fit the first seven categories, you can re-define 8 through 16 here. Just select the next number and type the category name in "Replace with" to rename it, then click OK.)
You will also need to create a short citation form.
Short Form Citations
When you get to your short-form citation, the process changes slightly. Once you've selected the short-form citation, you will click "Mark Citation" and then choose the proper category from the drop-down.
Make sure to click Mark. After you mark citations, Word may automatically show you field codes and hidden text. To turn this feature off, click the Show/Hide 
button on the Home tab in the Paragraph group.
Inserting a Table of Authorities
Once you've finished "marking" your citations, the next step is to generate the Table of Authorities. Find a place in the document where you want your table of Authorities. Type out the phrase "Table of Authorities" to use as your heading. Place your cursor a few spaces below this heading. Then, go to the References tab, the Table of Authorities group, and select Insert Table of Authorities.
In the dialog box that appears, you will be able to decide the tab leader you want, the format you want, and what category you want to show in your table of authorities (the default is All). When done, click OK.
To update your Table of Authorities, click to the left of the Table of Authorities. Everything should be highlighted. Click the Update Table of Authorities button under the References tab in the Table of Authorities group.
If you have Word for Mac, you should be able to follow the same directions provided above. The buttons and dialog boxes just might look slightly different.
Mark Citation button in References tab:
Mark Citation dialog box:
Insert Table of Authorities dialog box:
