How did the missions work?

Answer 1

The manned Apollo missions launched atop a Saturn V rocket to get into Earth orbit. After a couple orbits to get everything configured they performed what is called a TLI (Trans Lunar Injection) burn using the CSM (Command Service Module) engine and coasted through cislunar space between the Earth and the moon for three days.

Once they arrived at the moon they performed a second burn of the CSM engine, called the LOI (Lunar Orbit Insertion) burn. This parked them in orbit around the moon. Two of the astronauts on board, the Commander, or CDR, and the Lunar Module Pilot, or LMP) entered the LM (Lunar Module) and separated from the CSM, leaving the Command Module Pilot, or CMP, alone in orbit. The LM then performed its own engine burn to reduce speed and eventually land on the moon.

The LM was built in two halves. When the ground mission was over, the CDR and LMP separated the Descent stage of the LM from the Ascent stage, fired the engine, and lifted off from the moon's surface, leaving the Descent Stage on the moon. Once there they reconnected with the CSM, disconnected the LM (which then either crashed into the moon or entered a long period orbit about the sun, depending on the mission), and performed a TEI (Trans Earth Injection) burn, once again using the CSM engine.

After another three day coast through cislunar space, the CMP disconnected the Command Module from the Service Module exposing the heat shield on the bottom of the CM, entered Earth's atmosphere, and splashed down into the ocean to be recovered by the US Navy.