Saw at grocery store, beautiful! Would like to care for it properly
Sure! This article will help you to get started: https://www.gardeningknowhow.com/ornamental/bulbs/star-of-bethlehem/star-of-bethlehem-plant-care.htm
My ornithogalum plants are becoming yellow.
The articles linked below will give you all the information you need on how to care for your plant, whether it is the Star of Bethlehem or the Orange strain. Regardless, the Ornithogalum comes from a bulb so, after blooming, the foliage will die back naturally on its own and fresh shoots will reappear.