Maybe your Voltage Regulators didn't work out. What's the module did you use?
Capacitors between a power line and ground are like water towers, they provide the extra energy that a circuit might need for a few micro seconds, so that when the current the circuit uses changes rapidly, the variations are evened out by the capacitors, so that the regulator can just supply a steady current and not worry about constantly adjusting every nanosecond, just like what a water tower does for the pump.
This means that whatever is "filling" the capacitors doesn't see the high frequency current. The shorter length you run high frequency current, the better, because all wires are antennas and we don't want to radiate RF and make an accidental radio transmitter.
The tons of different capacitors are used because capacitors have some built in inductance and resistance that the manufacturers can never fully get rid of, so each capacitor is better at dealing with a different type of current. The big electrolytic deal with the large load spikes that are relatively low frequency, and the little ceramics deal with the small but high frequency oscillations that a microcontroller might make.
The voltage divider is probably because that IC tries to keep its sense pin at a fixed voltage, the feedback voltage. If the voltage divider divides by 5 and the feedback voltage is 1v, the output voltage will be 5v, because the chip will regulate the output such that the feedback pin is at 5v. Different devices have different feedback voltages.
This is a PDF of Voltage Regulators LM2576
. You didn't give a specific image of your circuit So i find a diagram see if that could be helpful.