How do I care for this plant over the winter?
Parasol plant? Scheffleras are commonly known as umbrella plant or umbrella tree, so that might be what you have. But also, there is currently being marketed a plant known as Mandevilla sun parasol, or parasol pink mandevilla. Is this what you have? If so, these are not indoor plants, although since they're tropicals they can't take a northern winter. You might try letting it go dormant - keep it in a spot protected from freezing temps (basements are often used) and water very sparingly. like once a month. It will quickly lose all its leaves, but when you put it back outside in the spring and start watering it fully, it should come back.
This article will answer your questions: https://www.gardeningknowhow.com/houseplants/schefflera/schefflera-plant-care.htm