But if I don't understand the system, how am I going to use it?
It's also weird that at least three people are in the "you gave so much neg rep now you can't give it anymore" category.
If I remember correctly, in my case the option to give neg rep just disappeared one day and I don't think I actually gave neg rep before it got disabled. So, well, it's weird.
I'll wait for an admin to say something