If your Vi can't use backspace, it's likely you are using the generic text editor that comes with the Raspberrypi
To install vim you will need superuser privileges which you can get from your instructor
Step 1) Login as pi
Step 2) Install vim
sudo apt-get install vim
sudo reboot
Opening/creating a file
To open vi from the terminal, use the command vi nameoffile.py
Typing the name of an existing file will open that file
Typing a new name will create a new file (Be sure to include .py at the end of the file name)
Editing a file
When you first enter vi it will be in command mode
In this mode you can press x to delete a character
You can also press dd to delete a line of code
To insert and add code you must first enter insert mode by pressing the i key
Once you are in insert mode you can start typing your code. To exit insert mode press the escape key
Exiting vi
To save and exit a file type :wq and enter in command mode.
To exit without saving type :q! and enter in command mode
VI COMMANDS
From Command Mode (press esc to enter)
:w → to save in vi without exiting
ZZ→ save a quit a file in vi
:wq → to save and quit in vi
:q! → to quit without saving in vi