I just got my Nexus 10 last week. Like you, I read all the tutorials and watched a bunch of videos to learn how to root it. In the end I decided to forgo the use of any toolkit and just used fastboot commands and discovered it's actually really easy to do. I'll provide the steps that I used and you can figure out where you are in that process and go from there.
You'll need to have fastboot on your computer, but if you still have WugFresh's tool kit installed it'll be there. You'll also want to download a custom recovery image & the latest SuperSU binary to your computer.
You can get TWRP Recovery from
TeamWin Projects - TWRP 2.6 - Nexus 10 | TeamWin (under "Download - Recover Image Method", click link to newest .img & make sure you select the .img file, not the .tar) To make things easier, save the file in the same directory as fastboot.exe, most likely C:\Program Files\WugFresh Development\data.
Download the SuperSU binary from
SuperSU Download
Once you got all the files you need,
Enable USB Debugging Settings>Developer Options>USB Debugging
Reboot to Bootloader
Hold Power + Vol-Up + Vol-Down until device boots into Bootloader
Connect device to computer & install drivers, if needed
Open cmd window and change the directory to where fastboot.exe is located
Verify that fastboot is seeing the device
fastboot devices
(it should return the serial number for your device. If it doesn't, you'll need to make sure the drivers are installed properly.)
Unlock Bootloader
fastboot oem unlock
On the tablet, it will ask if you want to unlock bootloader. Use Vol buttons on tablet to select "Yes".
Reboot.
If it gets stuck in a bootloop, hold the Power + Vol-Up + Vol-Down until you're back in the Bootloader. Use Vol buttons to select Recovery Mode and tap Power. When the droid w/ the Red "!" appears, hold the Power button and quick press the Vol-Up button. This should take you into stock recovery. Select Factory reset. Reboot. After a few minutes, the device should boot normally.
Transfer SuperSU zip to Tablet
Enable USB Debugging
Reboot into Bootloader
Flash Custom Recovery
fastboot flash recovery <recovery name>.img
Boot to Recovery Mode
Install SuperSU zip
Reboot
You should now be rooted. You can use a root checker app from the Play Store to verify or just launch an app that needs root like TiBackup. If it asks you to grant SU permissions you're rooted. Some tutorials have you install Busybox as well, but some don't mention it at all. I'm not exactly sure what that's for. I didn't install it and haven't had any issues running the apps I have that need root.