[Gimp-user] overlay image in Gimp 2.8.16 ?

[Dave Stevens <geek uniserve com>]

I routinely use the gimp for simple things and now want to use it to add
an image (image 2) to a background. I have modified the new image so
that its background is transparent. I have saved it as both a jpg
and .xcf. I have an existing .jpg image that I want to use as the base
layer with image2 on top. I see conceptually how to do this but am
basically lost in the layers dialogs. 

I want to add image2 to the existing image then export the merged image
as a jpg. The online tutorials I've been able to find are either
outdated or apply to some other platform/version.

I'm using Linux Mint 18.3. Will rtfm if pointed to one or a tutorial
would be useful too.

TIA

Dave