Not a hard job.
If you didn't get the seal, get it before you tear it down.
Put the steering wheel in the middle, use a strap to keep the wheel from rotating.
(NOTE: If the shaft broke you will need to center the wheel and center the front tires.
you will need to center the shaft so that the teeth line up in the middle of the ball nut gears, you can see it with the cover off.)
Take the nut and washer off for the pitman arm.
Mark the pitman arm to sector shaft, a good pen mark or punch mark so you know where to aline to the new shaft.
If you put this mark straight up that will help you install the new sector shaft in the same way.
Remove Pitman arm.
Remove the side cover that will pull the cover and sector shaft out, you can lightly tap the pitman end of the shaft to help it out.
Remove the adjuster lock nut of the ride of the cover, then remove the adjuster bolt to get the sector shaft to come out of the cover.
Pull old seal and install new seal.
Copy your marks to the new sector shaft paying close attention to the orientation.
Reverse all steps, making sure to keep the shaft in the same direction when reinstalling.
Adjust the lash on the side adjustment and reinstall the lock nut.
You can also get the WSM (aka Service manual) off Kubotabooks.com, might help with more details.