(USB keyboard + keyboard+lcd +due) using facing problem of getting same output

sir i'm got every key value on lcd after do as u suggest.i want to make a program to write on lcd using usb keyboard . but i'm facing some problem.

  1. how to erase using' back space button ' how controller got the information about my cursor position.
    my final objective is maintain the database of any organisation using due +lcd +usb key board.
    can u suggest any program that would be helpful for me to achieve my gole