how do i use my phone as a keyboard?

Answer 1

you must try install remote desktop application
they have 2 part
1 part will be installed on your pc
and other part will be installed on your phone

try this:
https://www.androidpit.com/use-your-phone-as-a-wireless-keyboard-and-mouse
http://www.howtogeek.com/161602/how-to-use-your-android-device-as-a-mouse-keyboard-joystick-and-more/
https://feelthecode.com/

Answer 2

Idk