Option Explicit On
Option Strict On

Public Class Form1

    Private WithEvents WebBrowser As New WebBrowser

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Me.Controls.Add(WebBrowser)
        Me.WebBrowser.Dock = DockStyle.Fill
        Me.WebBrowser.DocumentText = "<select name=""hour"">" &
                                     "<option Value=""00"">0時</option>" &
                                     "<option Value=""01"">1時</option>" &
                                     "<option Value=""02"">2時</option>" &
                                     "<option Value=""03"">3時</option>" &
                                     "</select>"
    End Sub

    Private Sub WebBrowser_DocumentCompleted(sender As Object, e As WebBrowserDocumentCompletedEventArgs) Handles WebBrowser.DocumentCompleted
        Dim Browser As WebBrowser = DirectCast(sender, WebBrowser)
        Dim Document As HtmlDocument = Browser.Document
        Dim SelectElement As HtmlElement = Nothing
        For Each Element As HtmlElement In Document.GetElementsByTagName("select")
            If Element.Name = "hour" Then
                SelectElement = Element
                Exit For
            End If
        Next
        For Each Element As HtmlElement In SelectElement.Children
            If Element.TagName.ToLower = "option" AndAlso Element.GetAttribute("value") = "02" Then
                Element.SetAttribute("selected", "selected")
                Exit For
            End If
        Next
    End Sub
End Class