How to paint different textures on one landscape...

I’m a total beginner to unreal engine and I’m having trouble figuring out how to paint different textures on my terrain… I can manage a single texture, but I can’t paint different terrains. When I got to Landscape/paint the target layers section is blank. I tried to use this to get ‘stuff’ there but I just got a black sphere… Plz help a newb.

Would also be nice if you could explain how to add foliage and water… Thanks so much guys.