Hello, i need help finishing my code

Hello i cant finish my code. What i basically need to do is (this is a rough transaltion to english)
Is make a A[4][7] matrix , then get the columns 4,5,6,7 displayed on the screen and then i need to somehow make the colums add up the numbers in the to a sum. For example the coulm for may have numbers 53,213,421,232 so my programm needs to add them all up 53+213+421+232=917, and like that with EACH of the columns.
I have manuaged to somehow make the matrix , get each of the columns displayed on the screen but i have no clue how to make it add them up to a sum.

This is what i manauged to make.
Also i was hinted that i should add

 int nTotal = 0;

and after that put

 (nTotal += maatriks[i][3]); 

in a loop somewhere? i didnt understand any of that.....

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

#define RIDU 4
#define VEERGE 7
#define MAX 150
#define MIN 10

int main (void)


{
	
	

int maatriks [RIDU] [VEERGE];
int i,j;
 

srand(time(NULL));



for(i=0; i<RIDU; i++)

{
for(j=0; j<VEERGE; j++)
{

maatriks[i][j]=rand()%(MAX-MIN)+MIN;
}
}



printf("Generated matrix is :\n\n");

for(i=0; i<RIDU; i++)
{
for(j=0; j<VEERGE; j++)
{
 printf("%4d", maatriks[i][j]);
}
printf("\n\n");
}



printf("========================================\n");
printf("Colums from the third to the right\n");

for(i=0; i<RIDU; i++)
{
for(j=0; j<VEERGE; j++)
{
 
 if (j>2)  printf("%4d", maatriks[i][j]);
}
printf("\n");
}
printf("========================================\n");


for(i=0; i<RIDU; i++)
{
    
}


printf("Fourth column and its sum\n");

for(i=0; i<RIDU; i++)
{
for(j=0; j<VEERGE; j++)
{
	        	(nTotal += maatriks[i][3]);
 if (j<1)  printf("%4d", maatriks[i][3]);
}
printf("\n");
}
printf("----------------------------------------\n");

printf("Fourth column and its sum\n");

for(i=0; i<RIDU; i++)
{
for(j=0; j<VEERGE; j++)
{
 if (j<1)  printf("%4d", maatriks[i][4]);
}
printf("\n");
}
printf("----------------------------------------\n");

printf("Fifth column and its sum\n");

for(i=0; i<RIDU; i++)
{
for(j=0; j<VEERGE; j++)
{
 if (j<1)  printf("%4d", maatriks[i][5]);
}
printf("\n");
}
printf("----------------------------------------\n");

printf("sixth column and its sum\n");

for(i=0; i<RIDU; i++)
{
for(j=0; j<VEERGE; j++)
{
	
 if (j<1)  printf("%4d", maatriks[i][6]);
}
printf("\n");
}
printf("----------------------------------------\n");










scanf("%d");


return 0;
}