Use Proxy

    <Runtime.InteropServices.DllImport("wininet.dll", SetLastError:=True)> _
        Private Shared Function InternetSetOption(ByVal hInternet As IntPtr, ByVal dwOption As Integer, ByVal lpBuffer As IntPtr, ByVal lpdwBufferLength As Integer) As Boolean
        End Function

        Public Structure Struct_INTERNET_PROXY_INFO
            Public dwAccessType As Integer
            Public proxy As IntPtr
            Public proxyBypass As IntPtr
        End Structure

        Private Sub UseProxy(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 = Marshal.StringToHGlobalAnsi(strProxy)
            struct_IPI.proxyBypass = Marshal.StringToHGlobalAnsi("local")

            Dim intptrStruct As IntPtr = Marshal.AllocCoTaskMem(Marshal.SizeOf(struct_IPI))

            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

        Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
            Label4.Text = (TextBox1.Text & ":" & TextBox2.Text)

        End Sub

        Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
            UseProxy(Label4.Text)
            WebBrowser1.Navigate(TextBox3.Text)
        End Sub
    End Class