Write a program to compute numeric grades for a course

You can add in to the program I made below. It is incomplete but you can use it so that you would have a quicker time to complete the program. Step by step explanations would help me since I am an online learner. The question is as follows:

Write a program to compute numeric grades for a course. The course records are in a file that will serve as the input file. The input file is in exactly the following format: Each line contains a student's last name, then one space, then the student's first name, then one space, then ten quiz scores all on one line. The quiz scores are whole numbers and are separated by one space. Your program will take its input from this file and send its output to a second file. The data in the output file will be the same as the data in the input file except that there will be one additional number (of type double) at the end of each line. This number will be the average of the student's ten quiz scores. Use at least one function that has file streams as all or some of its arguments.

// Class average program with counter-controlled repetition

#include <iostream>

using std::cout;
using std::cin;
using std::end1;

const int MAX_GRADES = 10
// function main begins program execution
int main()
{
int total; // sum of grades input by user
int gradeCounter; // number of grade to be entered next
int grade; // grade value
int average; // average of grades

// initialization phase
total = 0; // initialize total
gradeCounter = 0; // initialize loop counter

// processing phase
while (gradeCounter<MAX_GRADES)
{ // loop MAX_GRADES times
cout << "Enter grade:"; // prompt for input
cin >> grade; // read grade from user
total = total + grade; // add grade to total
gradeCounter = gradeCounter + 1; // increment counter
}

// termination phase
average = total / MAX_GRADES; // integer division

// display result
cout << "Class average is " << average;
return 0; // indicate program
} // end function main