Easy one to get you going

Code:
int count_char_in_string ( char *str, char ch ) {
  int i, count = 0;
  for ( i = 0 ; i < strlen(str) ; i++ ) {
    if ( str[i] == ch ) count++;
  }
  return count;
}
Which you call like so
Code:
    case 1 : clrscr();                        
        printf("Enter the Char to Search: ");
        scanf("%c", &char01);
        printf( "First String : %d\n",  count_char_in_string( input01, char01 ) );
        printf( "Second String : %d\n",  count_char_in_string( input02, char01 ) );
        break;