When you import a layer/image onto an already existing canvas, but that import is larger than the canvas... you do not get to see the whole import.

Questions:
1) Is there a way to see the whole import layer/image?
2) How do I manipulate that single layer, like resize and such so, or even cut n paste, beyond just that part that happens to be within the canvas? (Cause I been trying, but I cant get it done.)

I imported an image I wanted as background... But I only see the (top left) sky because it is larger than the canvas.
The ground and trees are somewhere below my canvas... and that is the bit I actually need.
I cant figure out how to resize it to canvas size, as I would do with any other image that IS within canvas size.
And I dont want to resize it fully down to canvas size as that would make the import too small on the canvas (they are not of the same X:Y ratio!).

I must be overlooking something really simple. But cant figure it out. Sorry about that.

After you imported the layer:
Press CTRL + SHIFT + A to make sure there is nothing selected.
Click on the imported layer.
Hit CTRL + T to use the transform tool. You will automatically see the full layer content. ( if nothing happens, just click on the canvas )
Hold SHIFT while dragging the corner to maintain the aspect ratio.

There's an even simpler solution: after import, making sure the imported layer is active, select Image/Trim to current layer.