Calorie burn q?

So my mum, saint that she is, went on a roundabout in the van the other day collecting gymn equipment for me from freecycle. I now have an excercie bike, a cross trainer and a twit stepper. However, my HRM hasn't arrived yet, hopefully it will come along soon, and I took my ipod/pedometer on with me. Ten minutes on the twise stepped and 757 steps done, I've managed to break a sweat, but...I have no idea how to even begin working out how many calories that is! Can someone help me?

Also our cros trainer upposedly meaures your heart rate as you ue it, not tried it yet though, but it doesn't calculate calories, so how would one go about tranlating the heart rate numbers to calorie numbers?