…Photoshop 10… a PSE 10 folder.
Photoshop Elements is not Photoshop. You want to post in the Photoshop Elements forum. Photoshop Elements forum
Also, make sure you have downloaded the appropriate version of the application for your platform, Macintosh or Windows.
This is not the Elements Forum, but perhaps you downloaded the Mac version, whose installer would be a .dmg file.
You say you installed it but you obviously did not, you only downloaded it and opened the downloaded folder.
I hope the original poster realizes that his thread has been moved to the correct forum here by the moderator/host.
If one folder is called README, what is the name of the other folder? And what does it contain? Other folders?