How to add dublicate image in a file ?

[gardenair]

Well, I try it once again to solve the issue. Following are the steps.

1- I use the default (Background layer) and then fill the colour with the bucket fill tool.
2- Add a new layer and assign it a name.i.e Hard Disk-1
3- Select the Background layer and then File...>Open...>Path of the image file
4-The file image is open, then Edit.....>Copy
5-Click on the Background layer at the top right side because it is not visible on the right side layer section.
6- The Background layer is selected, now I press "Ctrl +v".A copy of the image was created ,I just drag it on right side.A doted box was with the image .
7-As I did on the right side of the layer portion GIMP automatically created a new layer with the name "Floating Selection".
8-Now I click on "Background Layer" but GIMP shows a message at the bottom side "Cannot select an item while a floating section is active." 

Please guide me that why this message appears? Why floating layer was created automatically and what is its purpose?

9- By clicking on the main convas the floating layer (3rd layer) disapper and only two layers was on the layer panel. The reason I don't know.


Kindly view the screen short.

Thanks