Practical Information:
A capacitor is designed to hold an amount of energy. It's in that regard similar to a battery, but it stores much less energy and can charge and discharge much faster.
Wiring
If you want to wire the capacitor as a voltage stabilizer, you can wire it in front of the IC GND and VCC you want to stabilize. Make sure you wire it as close as possible to the IC and make sure the capacitance is about 2-3 times more than the spikes in power are likely to be.