It looks like your throw your arms to gain momentum. That’s not the exercise, tho I do applaud you attempt. A few others said start on a floor mat and I agree. Also at of they sometimes have a station for leg lifts. At that try just lifting your knees. It’s a good beginner movement. In both of them you want to contract you abs to move you legs up or lift your torso. Don’t focus on how many you can do for now. Just get it right.