When installing recessed lighting in an existing ceiling a hole is cut in the ceiling that exactly fits the profile of a special remodeling can to keep from damaging the surrounding drywall.
Installing high hats in existing ceiling.
Securely lock each clip by tapping it with a hammer and slotted screwdriver.
Repeat to connect and install the remaining recessed light housings.
Whether installing a new drop ceiling or mounting the recessed lights in an existing ceiling you need to address the electrical requirements of the lights and the additional support that each recessed light fixture will require.
Run nm b cable from the power source to a switch box and then to the first hole allowing at least 18 inches of extra cable to make wiring easy.
From above the ceiling find the existing electrical cable that comes from the wall switch and connect it to the new cable strung between the recessed lights.