Yáʼátʼééh! Even I cannot see the character when using the tablet computer, I guess you mean the letter / o + ̨ (I think it is the nasal vowel o) /, then I would type this as / náhookǫs /. Is it right?
Please, tell me if you are looking for a Navajo keyboard, and what platform is that you use in the exercises. Still, I do not use any Navajo layout in the desktop computer, on Windows 10, but only using Multiling Keyboard on Android. :)