[Gimp-user] Clipping path as alpha channel

[CaptBaldy <forums gimpusers com>]

Hello, complete noob here...

So I have an image that I need to edit/fix before submitting to a online vendor
for sale of the product in the picture on their website.  I have met all their
dimensional requirements and such but I have one that I am completely lost on. 
Their requirement is directly below:

"Outline Path: Main/Primary images should have an outline/clipping path around
the product (where applicable - no need to outline lifestyle images). This
outline/clipping path must be saved as a selection (alpha channel). TIFF
Transparency is not allowed."

Can anyone help me and explain what they are asking for and possibly how to do
this?  I have tried to figure it out myself but every time I think I have it I
end up with a file with just a white image subject with black background or vice
versa.

-- 
CaptBaldy (via www.gimpusers.com/forums)