png transparency issue

[marshallfox94]

FIGURED IT OUT NVM

Downloading transparent png on Google with a white transparent background:

I download the png. I open as layer. Then it shows a white transparent back that has not only white squares but light gray. When I move the image around the true transparent background shows. I have looked into countless forums and can't find a solution.

Some of the pngs I download do work. How do I know this? Because when I have my background photo and add the png over top that white transparent background doesn't show.
In fact, when I open it in GIMP I can see another darker gray and gray squared background that is the actual transparency. 

Say I want to have a mountain range background photo. Then I want to use a campire png that is only showing the logs and fire and no background, when I move that image opn top of the main background my image is showing a white background. Looking closely I can see there is indeed a white and gray squared background that is supposed to be transparent when adding it on top of another image. 

I have used the transparency > alpha selection > export as png and still doesnt work. I'm not gonna draw an outline of every single image that says it's supposed to be transparent, to get that transparent background. It's just not working.

What am I doing wrong? Are these images run threw another app that makes it lose transparency, say, Windows Paint?
The first image shows the 2 different transparent backgrounds.
The second shows a book that doesn't have a background since it's transparent but the other one does show that white background.

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[rich2005]

Well, the OP has figured it out, but just a comment for other users downloading images from an internet search. A possible scenario.

Many of the free-transparent-png sites are not that free. To get a good version, you need to register (or worse) and that info gets sold on (much the same as social media)
...so the user resorts to a right click and download this image which delivers a rendered image.  Might look like this, it was downloaded purporting to be transparent.

   

Apart from not showing anything under the image, things to look for.
The layer name for a non-transparent layer is bold
A real giveaway is when you can add an alpha channel to the layer.

This is what you should see:
The layer name in normal type
Add an alpha channel greyed out.

   

...of course they might be sneeky and make the rendered image with an alpha channel and a solid checkered background but not often