Remove the caster cups from their packaging. Place them near the casters of the piece of furniture you wish to protect.
Lift one caster by lifting the base of the furniture to which it is attached. Slip the caster cup under it.
Align the caster wheel so that it fits securely in the indentation of the caster cup.
Repeat for each additional caster. Check to see that each caster is firmly and securely positioned in the depressed center of the caster cup.
It is now possible to sit on a chair or otherwise put weight on any piece of furniture protected by caster cups.