Visual basic 2010 vbulletin Loader - vb.net

Question

I am trying to create a vbulletin Loader for my site.
The main question is how to create a loader for vbulletin
The Loader works so it has permissions from vbulletin; if a user is a V.I.P., then he/she has access to inject a V.I.P .dll. A regular user can't inject that .dll, only limited to some not all and they cannot download the .dll. I am currently working on the login and its not working, nor that secure.
Module1.vb code;
Imports System.Security.Cryptography
Imports System.Text
Imports System.Net
Imports System
Imports System.IO
Module Module1
Public Function Login(ByVal Username As String, ByVal Password As String)
Password = MD5(Password)
Dim valid As Boolean = False
Dim data As String = "vb_login_username=" & Username & "&vb_login_password=&s=&do=login&vb_login_md5password=" & Password & "&vb_login_md5password_utf=" & Password
Try
Dim request As HttpWebRequest = WebRequest.Create("http://www.mywebsite.com/login.php?do=login")
request.Method = WebRequestMethods.Http.Post
request.ContentType = "application/x-www-form-urlencoded"
request.UserAgent = "-- vBulletin Vaidation --"
request.ContentLength = data.Length
Dim rStream As New StreamWriter(request.GetRequestStream)
rStream.Write(data)
rStream.Flush()
rStream.Close()
Dim response As HttpWebResponse = request.GetResponse
Dim resReader As New StreamReader(response.GetResponseStream)
Dim str As String = resReader.ReadToEnd
If str.Contains("Successful Login!") Then
valid = True
Else
valid = False
End If
response.Close()
Catch ex As Exception
MessageBox.Show(ex.Message, "Error Failed to connect to www.mywebsite.com", MessageBoxButtons.OK, MessageBoxIcon.Error)
End Try
Return valid
End Function
Public Function MD5(ByVal number As String) As String
Dim ASCIIenc As New ASCIIEncoding
Dim strReturn As String = String.Empty
Dim ByteSourceText() As Byte = ASCIIenc.GetBytes(number)
Dim Md5Hash As New MD5CryptoServiceProvider
Dim ByteHash() As Byte = Md5Hash.ComputeHash(ByteSourceText)
For Each b As Byte In ByteHash
strReturn &= b.ToString("x2")
Next
Return strReturn
End Function
End Module
Form1 code;
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
MsgBox("Copyright Notice: Copyright website 2013 - 2014 All Rights Reserved. - Click 'OK' to lunch Loader.")
End Sub
Private Sub CheckBox1_CheckedChanged(sender As System.Object, e As System.EventArgs) Handles CheckBox1.CheckedChanged
If CheckBox1.Checked Then
My.Settings.mystring.Add(ComboBox1.Text)
ComboBox1.Items.Add(ComboBox1.Text)
My.Settings.Save()
End If
End Sub
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
If Login(ComboBox1.Text, TextBox1.Text) Then
MsgBox("Successfully Logged In!")
Me.Show()
Me.Close()
Else
MsgBox("Unknown Username and Password. Try Again.")
End If
End Sub