Help please.

Public Class Form1
    ' Proxy Structure
    Public Structure Struct_INTERNET_PROXY_INFO
        Public dwAccessType As Integer
        Public proxy As IntPtr
        Public proxyBypass As IntPtr
    End Structure
    Private Declare Auto Function InternetSetOption Lib "wininet.dll" _
    (ByVal hInternet As IntPtr, ByVal dwOption As Integer, ByVal lpBuffer As IntPtr, _
     ByVal lpdwBufferLength As Integer) As Boolean
    Private Sub RefreshIESettings(ByVal strProxy As String)
        Const INTERNET_OPTION_PROXY As Integer = 38
        Const INTERNET_OPEN_TYPE_PROXY As Integer = 3
        Dim struct_IPI As Struct_INTERNET_PROXY_INFO
        struct_IPI.dwAccessType = INTERNET_OPEN_TYPE_PROXY
        struct_IPI.proxy = System.Runtime.InteropServices.Marshal.StringToHGlobalAnsi(strProxy)
        struct_IPI.proxyBypass = System.Runtime.InteropServices.Marshal.StringToHGlobalAnsi("local")
        Dim intptrStruct As IntPtr = System.Runtime.InteropServices.Marshal.AllocCoTaskMem(System.Runtime.InteropServices.Marshal.SizeOf(struct_IPI))
        System.Runtime.InteropServices.Marshal.StructureToPtr(struct_IPI, intptrStruct, True)
        Dim iReturn As Boolean = InternetSetOption(IntPtr.Zero, INTERNET_OPTION_PROXY, intptrStruct, System.Runtime.InteropServices.Marshal.SizeOf(struct_IPI))
    End Sub

    Dim I As Integer = 0
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        If TextBox2.Text.Contains("http://") Then
            WebBrowser1.Navigate(TextBox2.Text)
            Timer1.Enabled = True
        Else
            MsgBox("You Have to Enter a Valid URL", MsgBoxStyle.Exclamation)
        End If
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Timer1.Enabled = False
        I = 0
    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        If I = 100 Then
            RefreshIESettings(TextBox1.Text) ' Set Proxy
            I = 0
        End If
        If WebBrowser1.ReadyState = WebBrowserReadyState.Complete Then
            WebBrowser1.Refresh()
            I = I + 1
        End If
    End Sub
End Class