Here's the correct syntax for the helper in VB:

@Helper MakeNote(content As String)
    @<div class="note" style="border: 1px solid black; width: 90%; padding: 5px; margin-left: 15px;">
    <p>
    <strong>Note</strong>&nbsp;&nbsp; @content
    </p>
    </div>
End Helper

Notice that the parameter is declared in a different way (content As String) in VB, compared to the C# way (string content).