"How Can I Edit Using Emacs"

[angelitos]

Dear Friends

I'm using a Mac with the system OSX (Unix based).
I get this instruction to change the number 2021 by the number
1792:

cd /System/Library/Extensions/com_cy_driver_USB_Device.kext/Contents
cp Info.plist ~/newinfo.plist
sudo emacs ~/newinfo.plist
(enter your password)
Ctrl-s 2021 Enter (locates the driver)
Backspace over the 2021 and replace it with 1792
Ctrl-x Ctrl-c y
sudo cp ~/newinfo.plist Info.plist
Restart


But when I find the number 2021 and try to use the
backspace to change the number I can't.

What can I do to change the number 2021 by the number1792?

Thank U
angelitos

Pd.
If you know somebody that is expert in Unix an use Mac OSX 10.1.5
please forward to him or her my question if you don't know how to
resolve it.