Led Matrix Power Supply

I built a 16x16 led matrix just like the schematics below(The schematics is for 8x8 matrix but i used the same logic to create a 16x16 matrix). I am going to use an Arduino uno to control all of these leds. I will use 74HC595 shift register to minimize the pins used. I will lit up 1 row at a time means a maximum of 16 leds at a time but i know that arduino cannot power 16 leds at the same time.

So i have to use an external power supply but i have no idea how to use an external power supply to power the leds and use the arduino just to control all of these leds. Please help me...