初级，怎么调用方法类？？？？？？？？？

/**//// <summary>
        /// 得到一年中的某周的起始日和截止日
        /// 年 nYear
        /// 周数 nNumWeek
        /// 周始 out dtWeekStart
        /// 周终 out dtWeekeEnd
        /// </summary>
        /// <param name="nYear"></param>
        /// <param name="nNumWeek"></param>
        /// <param name="dtWeekStart"></param>
        /// <param name="dtWeekeEnd"></param>
        public static void GetWeek(int nYear, int nNumWeek, out   DateTime dtWeekStart, out   DateTime dtWeekeEnd)
        {
            DateTime dt = new DateTime(nYear, 1, 1);
            dt = dt + new TimeSpan((nNumWeek - 1) * 7, 0, 0, 0);
            dtWeekStart = dt.AddDays(-(int)dt.DayOfWeek + (int)DayOfWeek.Monday);
            dtWeekeEnd = dt.AddDays((int)DayOfWeek.Saturday - (int)dt.DayOfWeek + 1);
        }


 /**//// <summary>
        /// 求当前日期是一年的中第几周
        /// </summary>
        /// <param name="date"></param>
        /// <returns></returns>
        public static int WeekOfYear(DateTime curDay)
        {
            int firstdayofweek = Convert.ToInt32(Convert.ToDateTime(curDay.Year.ToString() + "- " + "1-1 ").DayOfWeek);

            int days = curDay.DayOfYear;
            int daysOutOneWeek = days - (7 - firstdayofweek); 
 

            if (daysOutOneWeek <= 0)
            {
                return 1;
            }
            else
            {
                int weeks = daysOutOneWeek / 7;
                if (daysOutOneWeek % 7 != 0)
                    weeks++;

                return weeks + 1;

            }

　　}

我把上面的代码放进一个sqlhelper.cs文件里，现在要在后台调用，怎么调用？

1、如已知周数，求起始日和截止日
string week="25";//已知当前是第25周

2、已日期，求是当年中的第几周
string date="2013-07-03"//已知当前是第25周
[解决办法]

引用:

protected void Button1_Click(object sender, EventArgs e)
{
int yy = 2012;
int ww = 23;
DateTime dtWeekStart;
DateTime dtWeekeEnd;
DateTime str = sqlhelper.GetWeek(yy, ww, out dtWeekStart);
DateTime end = sqlhelper.GetWeek(yy, ww, out dtWeekeEnd);

TextBox2.Text = dtWeekStart.ToString();
TextBox1.Text = dtWeekeEnd.ToString();
}

我去 返回类型void你能那样用...


protected void Button1_Click(object sender, EventArgs e)
{
int yy = 2012;
int ww = 23;
DateTime dtWeekStart;
DateTime dtWeekeEnd;
sqlhelper.GetWeek(yy, ww, out dtWeekStart, out dtWeekeEnd);

TextBox2.Text = dtWeekStart.ToString();
TextBox1.Text = dtWeekeEnd.ToString();
}