protectedvoid Page_Load(object sender, EventArgs e)
{
    string strCurrDate = "Current date and time: " + DateTime.Now;
    DateTime dtYourDate = DateTime.Parse("09/02/2009 10:01:45 AM"); //September 2, 2009string strYourDate = "Your date and time: " + dtYourDate.ToShortDateString() + " " + dtYourDate.ToLongTimeString();
    string strTotalSecElapsed = TotalSecondsElapsed(dtYourDate).ToString() + " Seconds Elapsed";
    Response.Write(strCurrDate + "<br>" + strYourDate + "<br>" + strTotalSecElapsed);
}

privatelong TotalSecondsElapsed(DateTime dtYourDate)
{
    long lTotalSecondsElapsed = 0;

    //Find Current Date and Time
    DateTime dtCurrent = DateTime.Now;

    //Find Time Difference details between current date and your given date
    TimeSpan tsDiff = dtCurrent.Subtract(dtYourDate);

    //Add Total Seconds for Days difference
    lTotalSecondsElapsed = lTotalSecondsElapsed + tsDiff.Days * (24 * 60 * 60);

    //Add Total Seconds for Hour difference
    lTotalSecondsElapsed = lTotalSecondsElapsed + (tsDiff.Hours * 60 * 60);

    //Add Total Minutes for Seconds difference
    lTotalSecondsElapsed = lTotalSecondsElapsed + (tsDiff.Minutes * 60);

    //Add Seconds
    lTotalSecondsElapsed = lTotalSecondsElapsed + tsDiff.Seconds;

    return lTotalSecondsElapsed;
}