Where does the upload files stored in iPhone ?

well, I am wondering the same and I think the question is actually

what path(s) in the iphone's file hierarchy does Discover store the "Public" and "Private" folders, listed along with "Photos," that you see in the main interface for the Discover app in the iPhone.

This is something you'd be asking if you are looking at the contents of the iPhone's hard drive. If you could see those contents you'd notice that it's nothing like what Discover shows you, those three folders aren't even in the same folder together.

here's your answer:

./private/var/mobile/Applications/[random folder name]/Documents/Private:

./private/var/mobile/Applications/[random folder name]/Documents/Private/Transfer:

./private/var/mobile/Applications/[random folder name]/Documents/Public:

./var/mobile/Media/DCIM:
["Photos Folder"]

./var/mobile/Media/DCIM/100APPLE:

the [random folder name] is a way to make it hard for you to find the files. once you get to the Applications directory you'll see these folders.
Apple has the iphone do things this way on purpose. LAME.

Hey, I'm no terminal guru. i just figured this next step out. don't blame me if you mess around in the terminal. that's at your own risk.

from the terminal, if you know the name of a file in one of those folders you can use ls -R and then use the find function (usually command-f mac or control-f pc) and search for the name of the file.

Hope that helps!