I appreciate your fear and confusion! I use the elliptical mainly, and so I have made a vow to try to conquer the stair-stepper, but seriously I have a hard time adapting to it.
If you want to try again, remember that you don't have to go fast on the elliptical. In fact, I set it at pretty high resistance (I am up to slightly over half the maximum) and go slow, but still get a great workout. When I mentioned it to a physical therapist I was going to for tendonitis in my foot, he said that was great and it's very good for your core to set it at high resistance. So that makes me feel better when I see people bouncing around on it at high speed.
Also, the elliptical IS really hard at first, not just breaking yourself in to the unaccustomed motion, but in working muscles in ways they're not used to. I usually do 30-45 min at my home gym, but used a different elliptical machine on vacation I practically fell off with exhaustion after five minutes. You do get better at it with practice.
You might find some to tips to help you here (or at least get a laugh):
Cranky Fitness on the elliptical machine.