You need something called a wall anchor. I tend to use the heavy duty types, first using a drill bit to drill a large hole in the wall, then poking the anchor through, then securing it. They work really well. I've had a lot of success with these ones: https://www.homedepot.com/p/Driller-Toggle-1-8-in-x-2-in-DrillerToggle-Plus-Bolt-25-Pieces-360E/310377840