Proxy authentication?

Hello,

I am using a web browser object to fill in data of forms online, I am able to use proxies however I am unsure on how to enter the username and password for the proxy from a textbox?

code so far:

Code:

 <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

Button click:

Code:

UseProxy(Proxy.Text)
            WebBrowser1.Navigate("http://website.com")