csv files are just that, comma separated. You can't specify the cell because it is being read in line by line, comma by comma.
You can create an array and consider that index 0 is column a, index 1 is column b, etc. So if you want something in 1C you would put it in the array at $array['2'].
You can of course make it 2 deep in the array...
$array['2']['2'] = 'row 3, column c';