need help with char and ints in an array

below is a bit of a program that i am writing but at
the moment im having a problem with the array

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char start_board(char array[16]);


int main (void)
{
	
	char board[16];
	int countdown = 5;

	
	
	printf ("welcome to the block puzzle game\nyou must rearrange the numbers in to asending order\n\n");

	start_board(board[16]);

}

char start_board(char array[16])
{
	int index = 0;
	
	char board[16] = {'1','2','3','4','5','6','8','12','9','10','7','X','13','14','11','15'};

	for(index = 0;index<=15;index++)
	{
		if (index ==4||index ==8|| index ==12)
		{
			printf("\n");
		}
		printf ("%c  ", board[index]);
	}

	

	return board[16];
}

How can i get the output to print the two digit numbers in the array and still shox the X when it pops up

also i want to be able to scanf a integer and check if it is in the array although the array is in characters how would i do this

the main problem is that you didn't learn the C language well enough before jumping into your project. I suggest you read a book on the subject (lot's of tutorials online, too) before proceeding any further.