Displacemt Maps - shown while editing?

I need some help with a displacement map. I was doing a project for school where we had to make a map of the D-Day invasion, and I decided to do a 3D model.Being a chronic procrastinator, I left it to the last moment, and I need to know if I can get the displacement map of Normandy to show while I’m editing, as opposed to only during rendering.

Go to the modifier stack and select “Displacement”. Enter the name of your texture where it says Tex: . This will show the displacement map when in object mode.

Thanks, that seemed to work…

But now it’s repeating itself all over the plane.

How do I get it to strech itself over the entire thing?