how to create double entry book keeping for member purchases, fees, charges
Double entry accounting is a specialist skill by itself. To do this properly you'll likely need the assistance of someone trained in accountancy.

The basic principal is that every bit of money is associated with an account. Choosing what accounts and how they relate to each other is where the expertise lies. Money only ever moves between accounts via matching transactions - one to debit the source and the other to credit the destination.