I have two Custome Object 1. Students with having field of 
1.StudentName
2.joining
3.Duration
4.TotalAmount
and another object is 2. My Courses with having field of
1.CourseName
2.FeeAmount
3.TeacherName
student object will be perent and other will child how we can calculate sum of FeeAmount to the total amount using triggerd rollup summery..

I have two Custome Object 1. Students with having field of 
1.StudentName
2.joining
3.Duration
4.TotalAmount
and another object is 2. My Courses with having field of
1.CourseName
2.FeeAmount
3.TeacherName
student object will be perent and other will child how we can calculate sum of FeeAmount to the total amount using triggerd rollup summery..