[OT] GIMP howto ??

[Luca Manganelli]

On 11/18/05, Shot - Piotr Szotkowski <shot at hot.pl> wrote:
> Hello.
>
> Luca Manganelli:
>
> > if I do a "Image -> Size ... " (not Scale) to enlarge work area,
> > GIMP fills the additional area with an (much hated) alpha fill.
>
> > How can fill it with, for example, black color?
>
> By changing the background colour (in the toolbox window) to black
> and then making the layer you're editing expand to image size.

I tried to do this but it does not work. Can you explain me the
right steps to do it?