In
the Environment section of the
camera’s Attribute Editor (View
> Camera Attribute Editor), click the Create button
to the right of the Image Plane attribute.
Maya creates an image plane and connects it
to the camera.
Set
the Type attribute for the image
plane to Texture.
Click
the texture button for the Texture attribute.
The Create Render Node window
appears.
Select
the texture you want to use as a background (for example, an Environment
Texture).
Maya creates the texture and connects it to
the image plane.