How to make a Interactive Computer Screen in Unity 5.5?

Are there any API GUI editors that aren’t outdated?
I want a text based green text black backdrop command screen interactive computer.
I have the Computer’s Built in game objects, I have them set to be interacted with, how do I toggle from the character to the screen?

You can make a UI Canvas that looks like what you describe (black background, green text), make it visible a Camera only, then switch off your main camera, and turn on the Canvas camera.