How to get first and last day of given date using vb.net

How to get first and last day of given date using vb.net
Abstract
In page load event just call the GetFirstDayInMonth and GetLastDayInMonth it will return first and last day of the give date.

Partial Class _Default
    Inherits System.Web.UI.Page

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        If Not Page.IsPostBack Then
            MsgBox(GetFirstDayInMonth("#2010-06-19#"), MsgBoxStyle.OkCancel, "First Day of The Month")
            MsgBox(GetLastDayInMonth("#2010-06-20#"), MsgBoxStyle.OkCancel, "Last Day of The Month")
        End If
    End Sub
    Function GetLastDayInMonth(ByVal dtDate As Date) As Date
        Return DateAdd(DateInterval.Day, (Day(DateAdd(DateInterval.Month, 1, dtDate))) * -1, DateAdd(DateInterval.Month, 1, dtDate))
    End Function
    Function GetFirstDayInMonth(ByVal dtDate As Date) As Date
        Return Now.AddDays((Now.Day - 1) * -1)
    End Function
End Class