In Firefox on the tablet:

1. Tap on the menu button in the upper-right corner
2. Tap on Settings
3. Tap on Sync

You should be shown a twelve-digit code that you need to enter on your PC

Details here - How do I add a device to Firefox Sync?

This is not correct for me. When I :

 1.  Tap on the menu button in the upper-right corner
 2. Tap on Settings
 3. Tap on Sync 

I get a small popup box labeled "Sync" In the box I have one option to "Auto-sync app" with a check box to select. Under that it lists three accounts I can sync to, those are Google, Dropbox, & Firefox Sync.

It never gives me the code nor does it provide a place for me to enter it.

Has anyone figured this out yet? I do get an option to add a code but I don't get a code to enter on my computer.

After you click on your sync account there should be an option to pair a device and you can enter a code there. My only thing is I want the info from my computer. Will pairing my account make me lose all info on computer?

@jase33 Thanks for the screenshot - you already have sync set up on that tablet - that's why you see that menu.

Ok so if you want to pair your new PC with this tablet, do this:

1. Tap on Firefox Sync in that menu in your screenshot
2. On the next screen, tap on "Pair a Device" and you will get 3 empty boxes to enter a set up code.
3. Now on your PC... At the top of the Firefox window, click the Firefox button (Tools menu in Windows XP) and select Set Up Sync. The Firefox Sync Setup window will open.
4. Click I Have an Account.
5. The code to add this computer will be displayed.
6. Take that code and enter on your tablet.