I am trying to do a transparency inside image kind of effect

Question

This is what I have, I did the following effect by following the steps in this post:

How do I make this image in image effect?

Now what I am trying to do is instead of having the background in the back (in my case, the green city scape, I just want it to be transparent.) Is there a way to accomplish what I want? I tried erasing the bottom layer to make it transparent and make the top layer mode "lighten" but it doesn't do anything. I have some examples of what I am trying to accomplish if you scroll all the way to the bottom(they are the closest things I could find).

Here are some examples to sort of paint a better image of what I want. Don't be fooled by the Al Capone example (I don't want it to be cartoony, it's just an example).

Answer 1

So the question is different and the thought process is different but once you get to a really high level of understanding you'll know that the process is the same as this question: How do I blend a black-background fire image in Photoshop?

Most of the time its people wanting to remove the black or white background and leave the rest but the premise is the same and since that question was a black background my answer is also the same. If it was a white background or yours was a black background (really lighter / darker) then it would just be moving the slider in the opposite direction: