How to create login accounts

[Pantero]

Hi, I'm trying to create a program where a user has to login. However, I also want the user to create their own account and login with it whenever they want. For this I have 2 forms (frmLogin and frmCreateLogin).

frmLogin has a username, a password and a login button, aswell as a linklabel connecting it to frmCreateLogin, here is the code for it:

Public Class frmLogin

    Private Sub btnLogin_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLogin.Click
        'The purpose is to only allow a User with the right password and username to enter as Admin or Guest
        If txtUsername.Text = "Admin" And txtPassword.Text = "4321" Then
            'Show Main Menu
            frmMemberDetails.Show()
            'Hide this form
            Me.Hide()
        
        Else : MessageBox.Show("Username or password incorrect. Please try again", "Login Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
        End If
    End Sub

    Private Sub btnExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExit.Click
        Application.Exit()
    End Sub

    Private Sub lnkCreate_LinkClicked(ByVal sender As System.Object, ByVal e As System.Windows.Forms.LinkLabelLinkClickedEventArgs) Handles lnkCreate.LinkClicked
        frmCreateLogin.Show()
        Me.Hide()
    End Sub
End Class

frmCreateLogin has 6 fields and 1 button; they are:
Forename
Surname
Username
Password
Re-type password
Authentication password (The admins password, to authorize the creation of the account)
and 'Create Login' button

I haven't added any code to frmCreateLogin because I don't know where to start. Can anyone nudge me in the right direction, as I have no idea how to code this.

Thanks