Not all devices are compatible with the Google Play Store, which is often seen with the lesser-known brands. They usually rely on other 3rd party app stores like GetJar or SlideMe. You could always install the Amazon Appstore:
1. Go to
Settings>Security, and make sure "Unknown Sources" is checked.
2. On your tablet browser, go to amazon.com/amazonappstoreapp, and follow the instructions for download.
3. Open your Downloads shortcut, and tap on the Amazon Appstore installer.
It's highly doubtful that you'll get any official system updates from Coby. To give you an idea of their support, here's the link to their support page for your device:
Coby Electronics. Did you click the link? That's right, it's just a screen that says "Coby," with nothing else!
You could always do a Google search on how to root your device and see if there's anyone who has developed a ROM of a higher version of Android that you could flash.