Error CS0103: The name 'formatter' does not exist in the current context

Hello im beginner. so what am i trying to do is making save system with binary formatter but when i make save system script the formatter was not detected so what i have to do?
This is my program code

Sorry for my beginner mistakes, actually i found the problem with the variable name that must be lowercase.

You need to configure your IDE so you get autocomplete and error highlighting.
It should be very difficult to make basic mistakes like these, coding with an unconfigured IDE is a bad idea!