Display the path of the first attached media (single.php)

What do you mean by attached media?

I mean, the first image inserted in the post.
What code can I insert in my single.php file to display the full path of the first inserted image in the post the like in the following screenshot ?
https://static.dyp.im/jfoq513ojV/84026be18c9e062145d4c41538d43968.PNG

Does this help https://wordpress.stackexchange.com/questions/143644/get-id-of-first-image-attached-to-a-post

Unfortunately no, it doesn’t.
It just displays the image twice.

Surely it must help, if you’re getting the image now. Unless you were getting it before already? Can you provide more context? Which theme are you trying to integrate this into?

I’m using a theme called “Puzzles” from themeforest.net.
Actually, every time I post a wallpaper on my wordpress website, I have to manually write in the post: the dimensions of the wallpaper, the size and the format.
I’m looking for a WordPress function that will automatically search for those informations and display it in the post.
I see that WordPress already do that in the Media page, but I can’t reproduce it in single.php.
Here is a screenshot of what I’m trying to do : https://static.dyp.im/ymNB0mihfl/482dfbb3b20bc8b9b86937c42ab29945.PNG

And here is a screenshot of what I’m talking about (Media page) :
https://static.dyp.im/GyI62aJTll/c63676fde0ead57120fdfdfd4af4c1fe.PNG