How do I create an array inside a function and then access and send data to the array from main()? (No return needed)

Question

I have a function that I am trying to create, which has an attribute that is a two-dimensional array.

However, I am not sure what I am doing.

This is what I have:

class Savings : public Account {
    protected:
        string sTrans[2][2];
        
    public: 
        string transtype;
        void Transfer(string a, string b){          
            if (a == "Debit" || a == "debit"){
                double c = std::stod(b);
                acc_balance = acc_balance - c;
                transtype = "Debit";
            }else if (a == "credit" || a == "Credit"){
                double c = std::stod(b);
                acc_balance = acc_balance + c;
                transtype = "Credit";
            }
        }
};

My goal is to create the array, sTrans[2][2], and then store the data I receive from user inputs.