Good I have to cover a hole of ceiling light, since the plaster fell off when removing a ceiling and a hole was left a little bigger than it was.

Yawl Replace the missing material with plaster or interior Poximil; you can cross some fine wires to support the material if the hole is large, first load the plaster to make "body" in the hole, always slowly, then throw (maximum 10 minutes), more diluted loads to finish. Regards