columns and rows,

thus you draw all your LEDs as a square
then you connect the anodes (each with a series resistor) for each row of LEDs together
then you connect the cathodes for each column of LEDs together

Then a brief look will show that when you pull a row high (this will require an Allegro chip or some transistors) high and a column low only one LED will light up.

Make that drawing and things will become as clear as a lit LED :)

Erik

PS I state "Allegro chip" there are other manufacturers of suchm Allegro just happen to be the most common.