how to use fork function

[che wan]

hi...i'm a new in C language.it is my sample program but i don't know to include the fork function.

#include<stdio.h>
#include<math.h>

int a[50][50];
int b[50][50];
int c[50][50];
int i,j,m,n,p,q;

void main()
{

//clrscr();
printf("\n enter order of Anxn matrix: \n");
scanf("%d%d",&n,&m);
printf("\n enter order of Bnxn matrix: \n");
scanf("%d%d",&p,&q);
if(n!=p)
	{
		printf("\n additional is impossible \n");
	}
else
	{  printf("\n enter elements of matrix Anxn: \n");
		for(i=0;i<n;i++)
			{
				for(j=0;j<n;j++)
				{
					scanf("%d",&a[i][j]);
				}
			}
		printf("\n enter elements of matrix Bnxn: \n");
      for(i=0;i<p;i++)
			{
				for(j=0;j<p;j++)
					{
						scanf(" %d",&b[i][j]);
					}
      	}
		printf("\n order of matrix C is %dx%d ",n,p);
		for(i=0;i<n;i++)
			{
               for(j=0;j<p;j++)
					{				
					     c[i][j]=(a[i][j] + b[i][j]);
					}
   		}
      printf("\n\n matrix C is : \n");
      for(i=0;i<n;i++)
			{
				for(j=0;j<p;j++)
					{
						printf(" %d\t",c[i][j]);
					}
            printf("\n");
			}
   }
getch();
}

somebody plz help me!!!!
i need to send it soon

[whodgson]

main() must be of type 'int' ..........i think.

[Laharl]

You're correct. For fork(), #include <unistd.h>. Keep in mind that if you're working on windows, that file does not exist as it is the unix standard header (linux has it too).