Kodları Bulduğum site: https://rstforums.com/forum/topic/33773-vb-net-login-to-phpbb2-phpbb3-mybb-vbulletin-ipb2-ipb3-webrequests/
Hata veren kod kırmızı ile gösterim aşağıda vbulletin.vb classına koymam gereken kodlar var kırmızı ile gösterilen yer hata veriyor sondeki ( silincede hata veriyor.
Written by Webhouse @ HF, please add credits if you use this.
Public Class vBulletin
    Inherits Forum
    Public Sub New(ByVal url As String, ByVal username As String, _
  ByVal password As String)
  MyBase.New(url, url & "/login.php?do=login", username, "vbseo_loggedin", "yes")
  MyBase.logindata = "vb_login_username=" + username + "&vb_login_password=" + password + _
    "&cookieuser=1&s=&securitytoken=guest&do=login&vb_login_md5password=" + Md5String(password) + _
    "&vb_login_md5password_utf=" + Md5String(password)
    End Sub
    Public Overrides Function isLoggedIn(ByVal cookies As System.Net.CookieContainer) As Boolean
  If Not IsNothing(cookies.GetCookies(New Uri(url)).Item(defaultCookieName)) Then
    If cookies.GetCookies(New Uri(url)).Item(defaultCookieName).Value.Contains(defaultCookieSearch) Then
    Return True
    End If
  End If
  Return False
    End Function
    Private Function Md5String(ByVal v As String) As String
  Dim myProv As New System.Security.Cryptography.MD5CryptoServiceProvider
  Dim b As Byte() = System.Text.Encoding.ASCII.GetBytes(v)
  b = myProv.ComputeHash(
  Dim str As String = ""
  Dim i As Integer
  For i = 0 To b.Length - 1
    str = (str & b(i).ToString("x2").ToLower)
  Next i
  Return str
    End Function
End Class
  

