unity3d – Problem while Making Background in Unity 3D

I’m Following these steps
Follow these few steps to add texture as a camera background:

Create a new Canvas that would hold your image.
In that canvas, on Canvas component set:
Render Mode to Screen Space – Camera.
Render Camera to your main camera (drag&drop).
Plane Distance are the units, at which the background would render.
Right-click on the newly created canvas and create an Image inside of it.
On the newly created image on Image component:
Set Source Image to your desired background sprite.
and can’t insert my background also
can anyone help ?