The file you have edited is a font set. This defines a set of fonts to be used in case one of them is not installed on the end users PC. For example, say you had a font set of Heltvetica and Ariel. In the case where Helvetica was not present, the Ariel font would be used instead. The key element here is that the fonts are not installed on the end users PC. This has to be performed separately in Windows.
Thank you very much for your response. I believe the font is available because I can use it in Microsoft Word. Also, when I go to Control Panel>Appearance and Pdersonalization>Fonts it shows up (see image). Is there anything further you can think of that might be able to help me. Thanks!
Where do you want to use this? Just go into the CSS in a text editor and add the font to the style.
Thank you for your suggestion. I have opened my CSS and the entire family of HelveticaNeueLT Std is now appearing there.