How do u do stomach crunches

From here:

* You can do hundreds of these and still not feel it if you don't do it right. Do them slowly, tensing the stomach throughout for best results.
* Lie on your back and lift your shoulders off the ground, moving your ribs towards your hips - not too far, just keep it so you can feel your stomach working - and hold it for two seconds. Keep your head still, hands resting lightly on either side, but don't use them to pull yourself up - it is cheating and could strain your neck.
* Leg variations (getting progressively harder): Keep your legs bent and feet on the ground; keep your legs bent and feet in the air; have your legs straight out in front of you; or have your legs straight out in front of you and move them up and down in time with your torso.
* Arm variations (in ascending pain order): Across the chest; resting lightly on the sides of the head; or straight out above your head.
* Further variations: Rotate torso and lift the knees alternately so that each elbow (with hands resting on the head) touches the opposite knee; or you could try holding weights.