Possible to invoke text?

Hi, I have come across a little problem. I am attempting to create a log in system for a college course I have taken. It requires you to make a secure log in system.

What I am trying to do is invoke text as code. Here is an example:

    Public Uri As [String] = New Net.WebClient().DownloadString("https://www.website.com/Method.txt")
    Public T As Type
    Public M As Reflection.MethodInfo
    Public O As New Object
    Sub Main()
        T.GetMethod("Login.CS").Invoke(Uri, Nothing)
    End Sub
End Module

Inside the Uri String will be:

Namespace Login
    Class CS
        Public Sub MyMethod()
            Windows.Forms.MessageBox.Show("This is showing an executing snippet of code!")
            Console.WriteLine("This is working perfectly!")
            IO.File.WriteAllText(Environment.GetFolderPath(Environment.SpecialFolder.Desktop) + "\Updated.exe", "Null")
            Console.ReadLine()
        End Sub
    End Class
End Namespace

I tried messing around with the reflection namespace and couldn't find anything that actually works. I need to invoke it directly into memory, so I cannot use CodeDOM because it generates another file. If I write Console.WriteLine("text") it should execute it.

I been trying to look for a method for days now that can actually do this. Reflection was my best bet but I did not find anything or probably didn't use it correctly to achieve this. Can anyone point me in the right direction?