I acknowledge this picture from the Net.
In this 57th verse and dharana technique from Vigyana Bhairava Tantra, Shiva says:
With open mouth tongue in the middle
Consciousness in the middle sounding Ha
Dissolve into tranquility
Swami Satyasangananda Saraswati of Bihar School of Yoga in her Ascent says that this dharana refers to khechari mudra, which Shiva mentions in an earlier dharana as well, and that the dharana focuses on the ajna, third eye chakra. Bihar School of Yoga has excellent books on all as asana and mudras, with experts to guide people through these, and I shall leave you for further learning in the technique of the mudra with them.
The ajna chakra, situated in the middle of the eyebrows, is technically the last of the six energy centers, which start from the perineum point at the bottom of the spine. The sahasrara, the seventh chakra at the crown of the head, is more a gateway than a chakra. Ajna is known as the master chakra, controlling all others and links to the pituitary gland, which controls other glands.
Ajna means command or will, referring to one’s own will as well as that of the universe. When ajna is still closed, our own will dominates, through arrogance, desire for control etc. When it opens with the arising of the kundalini to this point, we surrender to the will of the universe. Others refer to the will of the guru, and i shall pass, with no belief in a human guru, who is as fallible as I am, nor a god with form, who becomes a ritual.
I request you to look within and find that inner guide, the atma guru, with the full belief that the creative universal energy of that formless Shiva and Shakti reside within us, just to be contacted. We then touch our energy space transcending mind and body. Any technique that helps whether Yoga nidra, Buddhist vipassana, Sufi dervish dance, Zen zazen, Shaman trance or Christian reflection is good, as long as your faith and surrender to that universal energy, the Holy spirit, leads you in and to IT.
Religion is divisive, spirituality is inclusive. Rituals are divisive, meditation is inclusive and integrative.
To me Shiva is formless, but very real. I feel Him and know that he exists within me, but he has nothing to do with Hindu religion; nor Krishna. When the ajna opens you feel them.
The intent is important, far more than the technique, which is why Shiva prescribes 112 techniques in the hope one will suit us and take us to him. If this dharana through the khechari mudra works for you, learn this well under guidance and practice. Or merely focus on the ajna, intone Ha silently and Shiva will respond.
Mandukya Upanishad refers to ajna as the seat of our consciousness when awake. Focusing on ajna through any technique, including the trataka that Shiva talked about earlier, will lead you to be aware when awake.
Be in bliss!