How to Move Terrain to Another Unity Project File?

Question

How can I import terrains onto another Unity project? I am new to developing on Unity.

I would like to place this terrain...

Onto this project. And as you can see...

Nothing shows!

So, how do I make the entire terrain appear on this Unity project file?

Since I am new to Unity, detailed explanations are greatly appreciated. Thank you for your help!

EDIT:

I added terrain data and now it looks like this

Answer 1

Import Terrain Data and replace missing textures within Terrain Layers.