Help me fix my c programming error.   #include #include #define _CRT_SECURE_NO_WARNINGS void addContact(); void viewContact(); char firstName(); char lastName(); char phoneNumber[10]; int main()

Help me fix my c programming error.

#include <stdio.h>
#include <stdlib.h>
#define _CRT_SECURE_NO_WARNINGS

void addContact();
void viewContact();
char firstName();
char lastName();
char phoneNumber[10];

int main()
{
int selection;
printf("\n\t---Contact Mangement System--");
printf("\n\t[1] Add New Contact");
printf("\n\t[2] View Contact");
printf("\n\t[3] Help");
printf("\n\t[4] Exit");
printf("\n\tEnter Your Selection");
scanf("%d", selection);
switch (selection)
{
case 1:
addContact();
break;
case 2:
viewContact();
break;
case 3:
exit(1);
break;
default:
printf("Enter Your Selection");
main();
}
}
void addContact();
{
printf("Enter First Name: ");
scanf("%s", firstName);
printf("Enter Last Name: ");
scanf("%s", lastName);
printf("Enter Your Phone Number: ");
scanf("%s", phoneNumber);
if (strlen(phoneNumber) == 10)
{
FILE* fp;
fp = fopne("contacts.txt", "w");
fputs(firstName, fp);
fputs(lastName, fp);
fputs(phoneNumber, fp);
printf("\n\tContact Added");
fclose(fp);

}

main();
}
  
void viewContact()
{
system("cls");
char rfirstName[20];
char rlastName[20];
char rphoneNumber[20];
FILE* fp;
fp = fopen("contacts.txt", "r");
fgets(rfirstName, 9, fp);
fgets(rlastName, 5, fp);
fgets(rphoneNumber, 11, fp);
printf("\n\t---Contact List---");
printf("\n\tFirst Name: %s", rfirstName);
printf("\n\Last Name: %s", rlastName);
printf("\n\Phone Number: %s", rphoneNumber);
main();

}