Level 1 is to keep the back on the mat with the legs in the air at any angle you want. The tailbone needs to stay connected to the mat though, so if it lifts, the legs are too low. While in this position with your back on the mat, lift the head and shoulders slightly while the arms are elevated at your sides. The arms will pump with each breath, like you're slapping water.
Level 2 is to lift the torso to a V posture with the legs, balancing on the tailbone. The knees are bent, and the arms are still at your sides, moving with each breath.Level 3 involves lengthening the legs while the torso is lifted.
Work your way into the posture that works best for you on any given day. Some days your hips might feel too tight to elevate the legs, other days you may just feel too tired to straighten the legs. It's completely up to you. Just remember to breathe in and out for 5 counts each, forcing those abs to MOVE with each breath.
In any of the levels, imagine you have a string connected to the top of your head, allowing you to pull and lengthen the neck. The spine must be straight if your torso is lifted. If you find that your back is curling, you're not yet ready to be in that posture. Take it down a level until you have full control over your posture.
Once you've counted 10 sets of inhales and exhales (100 total beats) you're done! Relax that body back on the mat and stretch.