This is definitely the biggest, and probably coolest, rocket I've ever made. Unfortunately, I don't have many pictures from the building process - but I'll show you around and explain how it works.
The most important thing to understand is that this is a special kind of rocket: it uses dual deployment. That means it releases 2 parachutes - 1 small one at the peak of its flight, and a much bigger near the bottom of the flight. This is done to prevent the rocket from drifting far because of the wind. Here's a diagram:
In order to accomplish this, this rocket has 2 compartments, one for the smaller parachute (the drogue chute), and one for the bigger parachute (the main chute):
In between the two parachute compartments is the electronics bay, which holds the dual-deployment altimiter needed to make this work:
The altimeter measures altitude based on air pressure (which is why the electronics bay has holes in it). It can sense when the rocket has reached its peak, so when it senses that, it sets off a charge in the drogue chute compartment, which ejects the drogue chute. Then, when it senses that the rocket has reached a predetermined altitude, like 500ft, it sets off another charge in the compartment for the main chute, which releases the main chute.
Bellow on the right you can see the container that holds that parachute ejection charge. On the left is an electronic connector to which an igniter will be attached. That way, the altimeter can set off the igniter at the correct time, which will in turn set off the ejection charge and release the parachute. This is the same for both the small and main parachute.