Preserve An Array Inside A Class Method?

I have been learning about OOP and classes from a book and one of the question is the book has asked to create a simple Saving/Checking accounts Program. The question says that most of the functionality must be done through an Accounts Class, and this Acoounts class must inherit certain private fileds from an base class 'Transaction.

The question also says that data from the Saving/Checking accounts Program must be read to and from a text file, and these functions must be done within the Acounts class.

i have done everything the question asks to the best of my knowlegde and understanding but when it comes to storing and retieving data from the textfile i cannot utilise the array i created to store the textfile data onto it.

Bank Account.Write a program to maintain a person's Savings and Checking accounts. The program should keep track of and display the balances in both accounts, and maintain a list of transactions (deposits, withdrawals, fund transfers, and check clearings) separately for each account. The two lists of transactions should be stored in sequential files so that they will persist between program sessions.

Consider the form in Figure 11.12. The two dropdown combo boxes should each contain the items Checking and Savings. Each of the four group boxes corresponds to a type of transaction. (When Savings is selected in the Account combo box, the Check group box should disappear.) The user makes a transaction by typing data into the text boxes of a group box and pressing the button. The items appearing in the Transactions list box should correspond to the type of account that has been selected. The caption of the second label in the Transfer group box should toggle between "to Checking" and "to Savings" depending on the item selected in the "Transfer from" combo box. If a transaction cannot be carried out, a message (such as "Insufficient funds") should be displayed.

The program should use two classes, Transaction and Account. The class Transaction should have properties for transaction name, amount, date, and whether it is a credit (deposit) or debit (withdrawal/check). The class Account, which will have both a checking account and a savings account as instances, should use an array of Transaction objects. In addition, it should have properties for name (Checking or Savings) and balance. It should have methods to carry out a transaction (if possible), to display the list of transactions, and to load and retrieve the set of transactions into or from a sequential file. The events InsufficientFunds and TransactionCommitted should be triggered at appropriate times.

Hint: In order for an Account object to display a list of transactions, a list box should be passed to a method as an argument. The method might be declared with Sub EnumerateTransactions(ByVal lb As ListBox).

Here is my code. I am sorry this code is basic and unedited.

Public Class Form3
'load contents of Text file into the listbox when first loaded
'store data in file into array of accounts, record no. counts

[code]....