Download the PND Manager from the PND Store. Then forget PNDStore. Use PND Manager.
I think it (the Store) automatically installs to "menu" The PND Manager lets you choose.
The first thing is to make sure your SD card is formatted correctly to FAT32 or EXT2 (I use and recommend FAT32...but there are some things that require an EXT2 format, as I understand...however, since you seem not too advanced at this stuff - like me - I'd use FAT32)
The best way to do this is to download the Panasonic SD Card Formatter to your PC...it's free, Google it.
Format your SD Card.
Now, make the following Folders in your SD Card:
Pandora
Under "Pandora" make the following folders:
Appdata
Apps
Desktop
Menu
Now download stuff you want.
If you want the icon to appear on the desktop, you need to save the .pnd in "Apps" or "Desktop"
Desktop will make it show up ONLY in the Desktop.
Apps will make it show up in Desktop AND Menu,
Menu, of course, makes it show up ONLY in Menu.
I'd be happy to help you however I can. do you live in the United States? If so, I might even be willing to talk to you on the phone to walk you through some of this...my payback, as someone here once did this for me, too!