How to get First Day of Month

DateTime now = DateTime.Now;
DateTime firstDay = new DateTime(now.Year, now.Month, 1);
string dayOfFirstDay = firstDay.DayOfWeek.ToString();

String day = System.DateTime.Now.DayOfWeek.ToString();
Int date = System.DateTime.Now.Day;
String fdm = System.DateTime.Now.AddDays(-Convert.ToDouble (date-1)).DayOfWeek.ToString();

Dim s = "201208"
Dim firstDay = Date.ParseExact(s, "yyyyMM", Nothing)
Dim lastDay = firstDay.AddMonths(1).AddDays(-1)
Dim year = firstDay.Year

The idea is that you use DateSerial to get 1st day of the month:-
VB Code:
DateSerial(Year(dtDate), Month(dtDate), 1)

To get the last day of the month you add a month to the first day then subtract 1 day which gives you
VB Code:
DateAdd("d", -1, DateAdd("M", 1, DateSerial(Year(dtDate), Month(dtDate), 1)))

string firstDayOfMonth = new DateTime(DateTime.Now.Year, DateTime.Now.Month, 1).DayOfWeek.ToString();