Lie of the floor with your knees bent, feet flat on the floor hip-width apart.
Place your hands behind your head, but don't lace your fingers together, have your elbows slightly rounded inwards. Have your chin slightly tilted towards your chest.
Slowly pull your abdominals inwards, and you'll curl forward so that your head, neck, and shoulder blades are off the floor. Pause, then lower. Keep your abs pulled in so you can feel the tension during the whole movement.
Be sure not to pull up on your neck, or bring your elbows in any more