Don't really have any code yet, Im not sure how to start this.
There are two forms:

Form1 Code:
Private Account As Collection

Private Sub Form_Load()
Set Account = New Collection
End Sub

Private Sub cmdAdd_Click()
Dim frmAccount As New frmAccount
frmAccount.Show
End Sub

Private Sub cmdExit_Click()
End
End Sub


Form2(frmAccount) Code:

Private Sub Command1_Click()
Account.Add (Text1)
Form1.lst1.AddItem (frmAccount.Text1)
End Sub