anode column, row??

hi!

i’m buying alot of parts off a site today and i need to know the diffrence between anode column, and rows, and cathode column, rows. i’m using it with the arduino, so i need anodes

obviously i need the anode’s to be hanging out, and for all i care they can have a common cathode, but what do i need, anode row or column, or cathode row or column?

please hurry, i want to place the order tonight!
thanks a bunch!!!
-big93