How to code Advanced Login System in vb.net?

here is my code
Dim logcn As New OleDbConnection("Provider=Microsoft.Jet.Oledb.4.0; Data Source=" & Application.StartupPath & "\Login.mdb")
Dim logda As New OleDbDataAdapter()
Dim logdt As New DataTable()
' Dim co As New OleDbConnection("Provider=Microsoft.Jet.Oledb.4.0; Data Source=" & Application.StartupPath & "\Login.mdb")
Private ConnnectionString As String = "Provider=Microsoft.Jet.Oledb.4.0; Data Source=" & Application.StartupPath & "\Login.mdb"
Private dn As New DataSet()
Dim mypath = Application.StartupPath & "\Login.mdb"
Dim Password = ""
Dim conn As New OleDbConnection("Provider=Microsoft.Jet.Oledb.4.0; Data Source=" & Application.StartupPath & "\Login.mdb")
Dim cmd As OleDbCommand
Dim cn As New OleDb.OleDbConnection("Provider=Microsoft.Jet.Oledb.4.0; Data Source=" & Application.StartupPath & "\login.mdb")
Dim sql As String
' Dim CMD As OleDb.OleDbCommand
Private Sub OK_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles OK.Click

Dim sql = "SELECT Username,Password,LoginAs FROM UserLogin WHERE Username = '" & UsernameTextBox.Text & "' AND Password = '" & PasswordTextBox.Text & "' AND LoginAs ='" & LoginAsCombobox.Text & "'"
Dim log = "SELECT LoginAs FROM UserLogin"
Dim loginas = "SELECT LogionAs FROM UserLogin"
conn.Open()
cmd = New OleDbCommand(sql, conn)
Dim dr As OleDbDataReader = cmd.ExecuteReader

' Dim connString As String = "Provider=Microsoft.Jet.Oledb.4.0; Data Source=" & Application.StartupPath & "\login.mdb"
' conn.Close()

Try
If dr.Read = False Then
conn.Close()
MessageBox.Show("Authentication Failed...")
Else
conn.Close()
'With ERA_DMS_HOME
' .LoginAsToolStripMenuItem.Text = GetUserName()
' Dim logform As New LoginForm1

Dim homform As New ERA_DMS_HOME
homform.Show()
Me.Hide()
'logform.Hide()
' End With

End If
Catch ex As Exception
conn.Close()
MsgBox(ex.Message)
End Try
If conn.State <> ConnectionState.Closed Then
conn.Close()
End If





End Sub