To practice jalandarabandha,
Sit in padmasana or sukhasana (normal cross leg posture), place your hands both on knee, relax all your body and close eyes. Most important sit straight, take a deep breath and exhale, do this one to three times or as much times to calm your breathing. Then take a deep breath and hold it, next bow your head and touch chin with chest.
That’s it this is the final position, stay relaxed and do it as long as you can hold your breath without any problem. After some time release head from that position and exhale and relax for some time. Repeat the kriya again after some time, you can do it as much times. This kriya can be done in another way also, by exhaling and holding your breath and then the same thing as said above. people with high blood pressure, heart problems, and mental problems are requested to practice it with the guidance of a yoga master only. This kriya benefits the nadi’s in head, thyroid, and parathyroid glands. Helps to cure imbalances in blood pressure, maintains sexual functions, cures mental problems like anxiety, anger, tension etc.