You don't 'add' fonts to InDesign, you install fonts in your system or, if you want the font to only show up in InDesign and not in other apps, you install them (put them in) in InDesign CC/Fonts.
Once installed (either on your system or fonts folder in InDesign) you can choose them to be used in InDesign.
But as this is basic computer knowledge I have a feeling you may mean something else...?
Presumably you mean Open Type Fonts. Which OS are you using?
Yes, sorry I didn't mention that I'm using ID on a windows 10 computer.
On Fri, Apr 1, 2016 at 4:46 PM, Frans van der Geest <