Help with source code!

The following is the code I have so far.I am having trouble with the code to read the input file in and creating the output file. I know I am supposed to us fopen() and fclose() but I dont know how. I am also having trouble with the code for using the array of structures and calculating the duration of the calls and charge of the calls once the file has been read into the program.


#include <stdio.h>
#include <stdlib.h>
#define discount 0.15
#define full_price 0.25
#define fed_tax 1.08
#define TRUE 1
#define FALSE 0


void Minutes(int [], int [], int [], int [], double *, double [], int *);
void Bill(int [], double [], double, double [], int *);
void Customer_Array(int, int[], int [], int [], int [], int [], double [], double []);
void Customer_Summary(int, double [], double [], double *, double *, double *);
void Total_Summary(int, int, double, double, double);

main()
{

  char response;

  int  s_hr[10],
       s_min [10],
       e_hr[10],
       e_min[10],
       call_count = 0,
       call_numbers [10],
       total_calls = 0,
       total_customers = 0;

  double duration [10],
         cost [10],
         start,
         total_minutes = 0,
         total_amount = 0,
         total_tax =0;


  do
   {
    do
     {

      Minutes(s_hr, s_min, e_hr, e_min, &start, duration, &call_count);
      Bill(call_numbers, duration, start, cost, &call_count);

      printf("\n\nIs there another call (Y or N)? ");
      fflush(stdin);
      scanf("%c", &response);
     }
    while  ((response == 'y') || (response == 'Y'));
      Customer_Array(call_count, call_numbers, s_hr, s_min, e_hr, e_min, duration, cost);
      Customer_Summary(call_count, duration, cost, &total_minutes, &total_amount, &total_tax);

      total_calls += call_count;
      s_hr [10] = s_min [10] = e_hr [10] = e_min [10] = call_numbers [10] = 0;
      duration [10] = cost [10] = start = call_count = 0;

      total_customers += 1;
      printf("\n\nIs there another customer(Y or N)? ");
      fflush(stdin);
      response = getchar();
    }
   while ((response == 'y') || (response == 'Y'));
   Total_Summary(total_customers, total_calls, total_minutes, total_amount, total_tax);
 }


void Minutes(int s_hour[], int s_minute[], int e_hour[], int e_minute[], double *start, double duration[], int *n)
 {
  double end,
         call_time;

  *start = s_hour[*n] + (s_minute[*n]/60.0);
  end = e_hour[*n] + (e_minute[*n]/60.0);

  if (*start > end)
   call_time = ((24 - *start) + end) * 60;
   if (*start < end)
    {
     call_time = (end - *start) * 60;
    }
  duration[*n] = call_time;
 }

void Bill(int c_num[], double c_time[], double s_time, double costs[], int *n)
 {
  double charge;

  if ((s_time > 8) || (s_time < 18))
   if (c_time[*n] > 60)
    {
     charge = full_price * c_time[*n];
     charge = charge - (charge * .10);
    }
   else
    charge = full_price * c_time[*n];

  if ((s_time > 18) || (s_time < 8))
   if (c_time[*n] > 60)
    {
     charge = discount * c_time[*n];
     charge = charge - (charge * .10);
    }
   else
    charge = discount * c_time[*n];

  costs[*n] = charge;
  c_num[*n] = *n;
  ++*n;
 }

void Customer_Array(int call, int c_num[], int s_hour[], int s_minute[], int e_hour[], int e_minute[],
                    double duration[], double charge[])
 {
  int number;
   printf("\nCall  Start time    Ending time   Duration    Charge");
  for (number = 0; number < call; ++number)
   {
    printf("\n%3d%8d:%02d%11d:%02d%10.0f%11.2f", c_num[number] +1,
             s_hour[number], s_minute[number], e_hour[number],
              e_minute[number], duration[number], charge[number]);
   }
 }

void Customer_Summary(int call_count, double duration[], double cost[],
                      double *total_minutes, double *total_amount, double *total_tax)
 {
  int number;

  double customer_time, customer_charge;

  for (number = 0; number < call_count; ++number)
   {
    customer_time += duration[number];
    *total_minutes +=duration[number];
    customer_charge +=cost[number];
    *total_amount += cost[number];
   }

  printf("\n\nThe total number of calls is:          %d", call_count);
  printf("\nThe total time used in minutes is:      %.0f", customer_time);
  printf("\nThe total charge is:                    $%.2f", customer_charge);
  printf("\nThe total tax is:                      $%.2f", customer_charge * .08);
  printf("\nThe total amount due is:               $%.2f", customer_charge + (customer_charge * .08));

  *total_tax += customer_charge * .08;
 }

void Total_Summary(int total_customers, int total_calls, double total_minutes,
                   double total_amount, double total_tax)
 {
  printf("\nTOTAL SUMMARY\n");
  printf("\nThe total number of customers:     %d", total_customers);
  printf("\nthe total number of calls is:      %d", total_calls);
  printf("\nThe total amount of tiem is:       %.0f", total_minutes);
  printf("\nThe total amount is:              $%.2f", total_amount);
  printf("\nthe total tax is:                  $%.2f", total_tax);
 }