New to Java

My problem says to create an account class with account number, balance, annual interest rate, and date created, and methods to deposit and withdraw. (which i have done) Then create two subclasses for checking and saving accounts. A checking account has an overdraft limit, but a savings account cannot be overdrawn. Implement the classes, write a test program that creates objects of account, savings account, and checking account, and invokes their toString() methods.

Ok so i have done the account class, created the subclasses and made toString for each savings and checking. What i don't understand is basically how to use the account methods for a checking/saving type account when the checking/saving are subclasses.

 public class ex9_3 {
    public static void main(String[] args) {
       
      //create new account 
      Account account3 = new Checkings();  
      Account account2 = new Savings();  
      Account account1 = new Account(1122, 20000, 4.5);  
      account1.deposit(3000);
      account1.withdraw(2500);
    
 
    //Print out required
    //Account
    System.out.println("\nAccount ID: " + account1.getID());
    System.out.println("Balance: " + account1.getBalance());
    System.out.println("Monthly interest rate: " + account1.getMonthlyInterestRate());
    System.out.println("Date created: " + account1.getdate());
    System.out.println("toString: " + account1.toString());
    
    //Savings
    System.out.println("toString: " + account2.toString());
    
    //Checking
    System.out.println("toString: " + account3.toString());
    }
  
}

class Account {
    private  int id;
    private  double balance;
    private  double annualInterestRate;
    private  java.util.Date dateCreated = new java.util.Date();
    
    // constructors
    public Account () {
    java.util.Date dateCreated = new java.util.Date();
    }
    //all variables included
    public Account (int id, double balance, double annualInterestRate) {
            this.id = id;
            this.balance = balance;
            this.annualInterestRate = annualInterestRate;
    }
    //setdate
    public void setdate(java.util.Date dateCreated) {
            this.dateCreated = dateCreated;
    }
    
    //return the date 
    public java.util.Date getdate(){
        return dateCreated;
    }
    
    //returning and setting each vars
    public int getID() {
        return id;
    }

    public void setID(int id) {
        this.id = id;
    }
    
    public double getBalance() {
        return balance;
    }
    
    public void setBalance(double balance) {
        this.balance = balance;
    }
    //deposit method
    public double deposit (double deposit){
        balance += deposit;
        return(deposit);
    }
    //withdraw method
    public double withdraw ( double withdraw) {
        this.balance -= withdraw;
        return(withdraw);
    }
    
    public double getAnnualInterestRate() {
        return annualInterestRate;
    }
    
    public void setAnnualInterestRate(double annualInterestrate) {
        this.annualInterestRate = annualInterestRate;
    }
    
    //monthly interest rate and formula
    public double getMonthlyInterestRate() {
        double monthlyInterest = (annualInterestRate / 1200) * balance;
        return monthlyInterest;
    }

}


//Checkings class
class Checkings extends Account {
   int overdraft = 400;

  public String toString() {
    return "Checkings Account " + "overdraft limit " + overdraft;
  }
}


//Savings Class
class Savings extends Account {

   int overdraft = 0;
  
  public String toString() {
    return "Savings Account"  + "overdraft limit " + overdraft;
  }
}