There are many ways to do twisting postures; in lunges, standing, seated, and laying down. The supine or reclining twists tend to be a little safer for people because of the support from the floor. A few of the more common twists are shown below.
In this first version called supta matsyandrasana or reclining lord of the fishes or simply knee down twist. The participant lays on the floor with one knee bent to start. An option is to give the twist a ‘head start’ by picking the hips up and placing them a couple of inches to the side you are twisting away from. Take the bent knee over to the opposite side. The arms can either extend in a T position along the floor or you can extend one and place the hand of the other over the knee to add a little weight which makes the twist a little deeper. The head can look straight up at the ceiling or you can look in the opposite direction to twist through the cervical spine in the neck as well. Only twist as far as feels comfortable. If letting the knee hang in the air is too much a bolster or block (or pillow- whatever is available) can be placed under the thigh or knee to add another level of support.
A deeper version is to take both knees to the side. You can come up onto the hip that you are twisting toward in this version or go to wherever is comfortable for you and your spine. The knees can drop to the floor as can the feet. To get a little work in the obliques on the sides of the abdominal wall you can drop the knees but leave the heels up. Looking away from the twist is always optional.
A third option for this pose is to take the legs in garudasana or eagle position. The upper body stays the same as the previous versions but the legs twist around each other. The top leg will wrap under the bottom leg in this version. The extra weight of the leg makes this a deeper version of the previous ones.
Whichever reclining twist you decide on, make sure that you are using compassion for yourself. Only go to the point that feels comfortable. These twists are not meant to be hard work, they should feel good. You should have no pain in your back, spine or anywhere else. Breath deeply allowing the the abdomen to expand as you inhale and contract as you exhale. Allow the upper body to fully relax and feel heavy.