How to get the day name from a selected date?
If you want to know the day of the week for your code to do something with it, DateTime.Now.DayOfWeek
will do the job.
If you want to display the day of week to the user, DateTime.Now.ToString("dddd")
will give you the localized day name, according to the current culture (MSDN info on the "dddd" format string).
System.Threading.Thread.CurrentThread.CurrentUICulture.DateTimeFormat.GetDayName(System.DateTime.Now.DayOfWeek)
or
System.Threading.Thread.CurrentThread.CurrentUICulture.DateTimeFormat.GetDayName(DateTime.Parse("23/10/2009").DayOfWeek)
//default locale
System.DateTime.Now.DayOfWeek.ToString();
//localized version
System.DateTime.Now.ToString("dddd");
To make the answer more complete:
DayOfWeek MSDN article
If localization is important, you should use the "dddd" string format as Fredrik pointed out - MSDN "dddd" format article