Just think of it as a rectangular grid.

int i[3][3];

3 elements across x 3 elements down.
[][][]
[][][]
[][][]

So if you did this:
Code:
int i[3][3];

i[0][0]=1;
i[0][1]=2;
i[0][2]=3;

i[1][0]=4;
i[1][1]=5;
i[1][2]=6;

i[2][0]=7;
i[2][1]=8;
i[2][2]=9;
You could imagine it like this:
[1][2][3]
[4][5][6]
[7][8][9]