Thats good to learn that you are purusing PhD and are willing to start pranayama. Find a comfortable seated position: Sit in a comfortable position on the floor or in a chair with your spine straight and your shoulders relaxed. Make sure your chest is open and your head is held in a neutral position.
Prepare your body: Begin by taking a few deep breaths in and out through your nose to help settle your mind and prepare your body for pranayama.
Close your eyes: Close your eyes and take a moment to focus on your breath.
Start with puraka (inhale): Slowly inhale through your nose, feeling the breath enter your body and fill your lungs.
Hold the breath: Hold the breath in for a moment before starting the next step.
Perform rechaka (exhale): Slowly exhale through your nose, feeling the breath leave your body and empty your lungs.
Hold the breath: Hold the breath out for a moment before starting the next step.(This should depend on your capacity and you should adopt this only when your stamina is good enough to do so.)
Repeat: Continue repeating this cycle of inhale, hold, exhale, and hold for several rounds, focusing on your breath and the sensation of it entering and leaving your body.
Release: Once you have completed several rounds of pranayama, release your breath and open your eyes. Take a moment to notice how you feel and how your body has been affected by the practice.
It's important to note that everyone's body is different, so it's always best to start with shorter rounds and gradually build up to longer sessions as you become more comfortable with the practice. As always, it's best to consult with a doctor or certified yoga instructor before starting any new exercise routine.