need help Nexus 9 stuck in endless reboot loop need help here. I to tried rooting my Nexus 9 and have ended up getting it into an endless loop of it trying to optimize apps. 

I did see Firelord's post to do this...

Using Firelords' and Jan's suggestion is was able to unbrick my device and get it working again.

Downloaded the Lollipop 5.1.1 image for Nexus 9 on this site: https://developers.google.com/android/nexus/images
Unpacked all the files into the folder where I had fastboot.exe.
Started my tablet by holding down the power button and the volue up botton to get into some kind of recovery mode.

Being new, what I don't understand is how do I get that file into the Nexus 9 if I can't get it to stop the boot cycle. I am pretty good following directions if there is some step by step way to get out of this mess.

Thanks for any help!
Bear in mind the following will wipe your device data:

To flash the firmware to your device:
While boot-looping, hold the power button until the screen goes blank. As soon as it does, hold the volume down button and your device will reboot into fastboot mode. From here, follow the instructions on the Nexus Factory Images to flash the firmware by flashing the bootloader and then the rest of the system using fastoiot on a connected PC. After this, you can run fastboot reboot if you're device doesn't automatically boot into Android.