Bunny Ear Cactus (also known as the polka dot cactus) are fairly easy to care for. All they require is a place where they can get lots of sunlight, water, and mineral-rich soil. Yours looks like it has appropriate soil, so just remove the plastic and place it in a pot or in the dirt outside. The picture makes it hard to tell, but I would give it about a cup of water each day. (Cup as in the measurement, not an actual cup.)

A cup of water a day will kill your cactus. It needs to be watered when the soil is dry.

What do I need to keep it alive and growing. Thanks.