instead of now i want the details keyed in the form

Question

string insert =

@"INSERT INTO Leave( LeavesTaken,Days,Reason,StartDate,EndDate,Status,UserId, Ishalfday) VALUES

( '{0}', '{1}', '{2}','" + DateTime.Now.ToString("yyyy-MM-dd") + "','" + DateTime.Now.ToString("yyyy-MM-dd") + "', 0,'{3}',0)";

 how  do i change instead  of now simply just convert it to string