How come I only Got 3 Textures.

When i got to add Textures there only are 3 textures and there not textures i need how do i get textures like dirt and sand and grass do i make it or can i download it somewhere?

Either. Unity has some ot those textures in terrain asset.
You can make them in program or dowload them. Just be vary on legal issues.

You can start here.