When the regular keyboard appears, long-press on the textfield.
Select the keyboard of your choice.
It this app doesn't appear in the list, see below - 'How to install'. To switch off the sound hit the mute-button on the keyboard.
To change the volume go to Settings/Language & Keyboard.This app is a keyboard replacement and not a standalone app.
Like every custom keyboard it has to be activated (first time only)* How to install Go to Settings/Language&Keyboard
Check the box for Typewriter Keyboard.
Use the back-button to go back to the homescreen