lay flat on your back, with your hands by your side (not under your butt) and do leg lifts. Keep your knee straight and your feet should go up to anywhere from 90 degrees, to being parallel with your eyes. Also, don't rest your legs on the ground between reps, keep them elevated roughly around 6 inches. This will help with the lower stomach.
For your sides, either do crunches on your side, or lying on your back, with feet flat on ground (obviously knees are bent)try to reach your hand to meet your ankle on the opposite side through the gap between your butt and feet. Meaning, take your right hand and try to reach your left ankle, and vise versa. The only movement you make is your waist. It's hard to explain, but i hope that helped!!