I am Creating Attendance windows form I have two lables 1-current time 2- time i fixed ie 8:00:00am.i want if student came to school before 5 minutes It show message you came before 5minutes and if student came after time 5 minutes late it show student came 5 minutes late

With .Net, you have two types of variables that will be usefull to solve your problem :
DateTime and TimeSpan. The last one is the difference between two DateTime. So you can write something like :
DateTime t1;
DateTime t2;
TimeSpan delta = t2 - t1;

TimeSpan embarks a bunch of methods to convert into differents units.