Public Class WebForm1
    Inherits System.Web.UI.Page

    Private Function GetHiddenField() As HiddenField
        Return CType(FindControl("HiddenW"), HiddenField)
    End Function

    Private Function GetLabel() As Label
        Return CType(FindControl("LblMessage"), Label)
    End Function

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
        If Not IsPostBack Then
            GetLabel().Text = "Page loaded for the first time."
        End If
    End Sub

    Protected Sub BtnStore_Click(ByVal sender As Object, ByVal e As EventArgs)
        GetHiddenField().Value = "43854"
        GetLabel().Text = "Value '43854' stored in hidden field."
    End Sub

    Protected Sub BtnRetrieve_Click(ByVal sender As Object, ByVal e As EventArgs)
        Dim value = GetHiddenField().Value
        GetLabel().Text = If(String.IsNullOrEmpty(value),
                           "Hidden field is empty.",
                           "Retrieved value: " & value)
    End Sub
End Class