"I downloaded a font and I want to use it in Microsoft Word. The font is currently on my desktop, but it doesn't show up in the fonts list in Microsoft Word. How can I add this new font to Microsoft Word."
All Microsoft Office applications pull the available fonts list from the system fonts stored in the Windows directory. You need to install the font in the Windows Fonts folder in order to access the font from Word, PowerPoint, Excel or any of the other Microsoft Office applications.
Most fonts downloaded from the internet are delivered as a .zip file. To install the font, you need to unzip the file using something like 7zip or the built-in Windows Extract feature. After you unzip the font, locate the .TTF file that is the font. Right-click this file and choose Install from the right click menu. The font should automatically install in the Windows Fonts folder and be available for use in every application on your system.
The other way to install a font is to browse to C:\Windows\Fonts and copy the font from your desktop to the Fonts folder, which also automatically installs the font on your system.