How do I add water to my island

I am extremely new to unreal engine having come from unity. In unity when I want to add a folder containing assets I just drag the folder into the assets folder but with unreal I want to add a folder containing some ocean water pack and I put it in the content folder but it doesn’t show up in the content browser as a folder all I want is to add water to my island so I can see the rivers and the sea nicely so i can get a good contrast other than just grass. Unity has default water things with animations and waves and is slightly see-through I was wondering if there is any easy way to drag and drop a flat cube of water that I can expand to be water for my island please help