How to check if a Graph is a Planar Graph or not?

I'm learning about the Planar Graph and coloring in c++. But i don't know install the algorithm to do this work. Someone please help me?

Here i have some information for you! This is my code! And it still has a function does not finish. If someone know what is a "Planar Graph", please fix the Planar_Graph function below! :D thanks so much! :x

# define MAX 100

int kt[MAX];
int tk=0;

int my_array[MAX][MAX];      // Graph
FILE *f;
int n,m;            //m: Edge, n: Vertex
int index[MAX];            
int ke[MAX];      
int Color[MAX]   ;      //Color Array
int colors_max;      
char filename[MAX];

int input(char filename[MAX])   
{
    int i,j;

    f = fopen(filename,"r");
    if (f== NULL)
    {
        printf("\n Error \n");
        return 1;
    }
    else
    {
        printf("File mane: %s \n",filename);
        printf("Content   :\n");
        fscanf(f,"%d",&n);
        fscanf(f,"%d",&m);

        for(i=0;i<n;i++)
        {
            for(j=0;j<n;j++)
            {
                fscanf(f,"%d",&my_array[i][j]);
                printf("%d   ",my_array[i][j]);
            }
            printf("\n");
        }      
        return 0;
    }   
}

void Default()   

{
    for(int i=0;i<colors_max;i++)
    Color[i]= i;
}

void Init()             
{
    filename[0]=NULL;
    n = 0;
}


int Planar_Graph(int my_array[MAX][MAX],int n, int m) // This is my problem
{

    /* for(int i=0;i<n;i++)

        if(n>=2 && (int)(n+1)*(n-2)/(n-1)>=m)
        return 1;
    }
    else
    {
        return 0;
    } */

}

int max()
{
    int max;
    int count=0;
    for(int i=0;i<n;i++)
    {       
        count = 0;
        for(int j=0;j<n;j++)   
            if (my_array[i][j] > 0)   
                count++ ;
        if (max < count)      
            max = count;
    }
    return max+1;
}

void Check(int x,int y)      // Check around
{
    int i;
    Default();         
    for(i=0;i<n;i++)
    {