Take your seat and Met-In box out, take the front black plastic panel out (directly below the seat, right behind where you put your feet when you're riding).
Now, look along the left-hand side of the frame. You'll see the ignition coil and wire. Follow that down to the left-hand side of the cylinder to the spark plug.
The torque for the spark plug is supposed to be 6.5 ft-lb according to the manual, but I use 10 ft-lb.
If you don't have the service manual for your Yager, you should get it. It's invaluable. I've got it if you want it, but it's kind of hard to email... it's 11.4 MB in size.
I've also got the parts list for ordering new parts, and the wiring diagram, if you need them.