You've bought a standard Kindle e-reader (sounds like the
$69 one), you can load books and other documents on it (and some basic active content as ixtab says), but it's not a tablet like the Kindle Fire that you can run apps on.
The closest you can get is to press the menu button while reading and it brings up the book title, time, WiFi and battery icon along the top status bar, although that is for the Kindle Keyboard, not sure if it works the same way for the Kindle 4?