On Linux Mint, you can get special characters by using the right Alt key. Press the right Alt key, and then then press the special character. Hold the Alt key in, like it’s shift. For example, to get é, hold in Alt, and press “‘”. To get ê, hold in Alt, and then press “6” (where the “^”) is situated.
You can change what’s called the “Compose” key should you require to do so. Go to:
Keyboard / Layouts tab. Options. Position of Compose Key
On our system this is fourth from the bottom.
Windows is more complicated you have to know the keycode. For example, ê is ALT 138 on the numeric keypad.