How to display the week number in C# after selecting the from date and to date from the calendar

public class DateHelpers
    {
        /// <summary>
        /// Gets the current week number.
        /// </summary>
        /// <returns></returns>
        public static string GetCurrentWeekNumber()
        {
            var weeknum = Thread.CurrentThread.CurrentCulture.Calendar.GetWeekOfYear(DateTime.Now, CalendarWeekRule.FirstFourDayWeek, DayOfWeek.Monday);
            return DateTime.Now.ToString($"{DateTime.Now.Year}-W{weeknum}");
        }

        /// <summary>
        /// Gets the current week number for a specified DateTime object.
        /// </summary>
        /// <param name="dateTime">The date time.</param>
        /// <returns></returns>
        public static string GetCurrentWeekNumber(DateTime dateTime)
        {
            var weeknum = Thread.CurrentThread.CurrentCulture.Calendar.GetWeekOfYear(dateTime, CalendarWeekRule.FirstFourDayWeek, DayOfWeek.Monday);
            return dateTime.ToString($"{dateTime.Year}-W{weeknum}");
        }
    }