How does one enter Hebrew cantillation marks into a Word document?

You need a program such as Davka writer. without software, you can do it manually by opening up the character map on your computer, but this is VERY tedious. you would just click on each character, copy it, and then paste it.

You can also find the Entire Tanakh online with cantillation marks. See http://www.mechon-mamre.org/c/ct/c0.htm