Interrobang as a Special Character

Trying to figure out how to add an interrobang character to my font. If I create it as a special character, how do I know what the keystroke is to get it to appear?

Please read the Unicode tutorial.

Not your concern when making the font. Just add it with the right name, and it will have the right Unicode value set. People can have a keyboard layout (or other input methods) to enter it or not. You have no influence on the user’s input method from within the font.

You don’t need to add interrobang as a special character. Just add a glyph with the name “interrobang”