There is a Stanley bostitch model B2000 stapler in my classroom. I need to fix the spring that advances the staples and holds them in place! wehre do connect the spring?

The person that asked this is probably long gone, but in case anyone else comes across this... I had the exact same problem when I dropped this same stapler today and the spring came out. After examining it for a bit, I realized where the spring had to go and fixed it.
Open the stapler the same way you would as if you were replacing the staples and look at the top piece, towards the back. There will be an elongated black hook here to attach one end of the spring. The trick is where you route the spring after that... look towards the front end of the same top piece, and you'll see 2 holes in the metal. You need to push the spring up through the first hole, then pull it back down through the second hole (you may want to use a straightened paper clip to snag the spring so you can pull it through that second one), and only then do you attach the other end of the spring to the hook in the sliding metal piece that advances the staples in the staple holder.
And that's it!