Good your tablet should already be rooted.
If you want Google Play try the following.
Download, but DO NOT INSTALL the Google Play apk provided by Casperischinky. The link is...
Open ES File Explorer. (If you don't have this yet, it is free and available at Amazon Appstore)
At the bottom left of the screen there are 3 vertical dots. Press this button.
A menu pops up, press settings.
Scroll down to Root settings and check all boxes available.
The program will ask some questions, answer yes to all questions.
The program will verify whether or not the tablet is rooted,
if it is, you will be able to continue until all 5 boxes are checked.
(If you can't get all 5 boxes checked it means your tabet is not rooted and you will not be able to proceed with the following until it is.)
Use the back button to get back to the main ES File Explorer screen
Navigate to /sdcard/Download/
Select and copy the Google Play apk you downloaded earlier.
Navigate to /system/app/
Select & paste the file into the folder.
(Don't be surprised that it seems to disappear, its made up of many smaller files)
Back out of ES File Explorer.
Shut down the tablet.
The next time you boot up you should have Google Play in your list of apps.