how am i going to use transistors to control the the current for each layer?

i wanna build a 2x2x2 led cube on my breadboard. i currently have uno, some leds, soldering iron and some jumper wires. i read some post online saying that i have use transistors for each layer, i wonder how that works because i don't see any transistor on top of each layer.

neither do I, but I have no idea what your looking at

For layer 1 you will have 4 IO pins connected to current limit resistors and then to the 4 LED anodes. All 4 cathodes will connect to the collector of an NPN transistor, emitter to Gnd. 5th IO pin to 270 ohm resistor to NPN Gate.

For layer 2 you will have the same 4 LED anodes connected to the 4 anodes from layer 2. All 4 cathodes will connect to the collector of a 2nd NPN transistor, emitter to Gnd. 6th IO pin to 270 ohm resistor to NPN Gate.

Drive the anodes, turn on transistor 1 for 5 mS. Turn off transistor 1. Drive the anodes, turn on transistor 2 for 5 mS. Turn off transistor 2. Repeat. Occasionally, change what you drive out on the anodes.

Exand the number of anodes, layers, transistors to make a bigger cube.

oh, thanx, i now have a sense of what to do now, okay, so my last question is that how do i connect the transistor to the cathode on the second layer? and how i control the transistor to be on and off(sorry for being a noob.), through programming?

Generally, folks seem to bend the "layer" pins out at a right angle (cathode in this case), and leave the column pins straight to connect to the LED below it anodes in this case).