You know, I might as well come and defend myself...
There's a big squareish loop-de-loop around a special ring, after a platform with an invincibility item. When you're running downward, you need to jump off and do Sonic's double-tap forward boost thing (what IS that called, anyway?). You should sail over some spikes and a spring, and you'll also see a rail above you. You should land in a lower area. Keep going from there, and you'll eventually get to the rail that leads to the final special ring (slow down after the bouncing walls to insure that you hit the spring which leads to that rail). The end really isn't far from there.