Python Counter - Convert to a Class

[Larz60+]

you need to learn the basics of classes.
I would expect the 'classes basic' post will contain enough information to complete your task, but I include all, if you wish (or need) to read further:
classes basic
Class Intermediate: Inheritance
Class Intermediate: Operator Overloading
Classes [advanced]: Dependent attributes (and Descriptors)
Classes [advanced]: Descriptors (managed attributes)