NASM--Apollo to the Moon--Preparing for Descent to the Moon

PREPARING FOR DESCENT TO THE MOON
To prepare for the lunar landing, two of the astronauts donned their protective spacesuits and moved to the LM. The lunar module was undocked from the command module, where one astronaut remained in lunar orbit, monitoring the activities of his colleagues. The two astronauts in the LM fired its descent-stage rocket engine. Directing the craft toward the surface; the astronauts controlled the descent rate to ensure a smooth touchdown.
To leave the craft once it was on the Moon, the astronauts attached lunar visors to their helmets and life support systems to their suits before they exited through the door hatch above the ladder.
To rejoin the command module, the astronauts fired the ascent-stage rocket engine and lifted off, leaving the descent stage on the Moon. The ascent stage met and docked with the command module in lunar orbit. The ascent stage then was programmed to crash into the Moon.

Lunar Module Cockpit