Guru Rinpoche, Padmakara, The Lotus Born (often referred to in the West as Padmasambhava, though this is actually simply one of his manifestations), is perhaps the most important figure in Tibetan Buddhism. He is widely regarded in Tibet as the Second Buddha. Space does not allow for even the briefest introduction to Guru Rinpoche, but the reading list at the bottom of this page, though not comprehensive, refers to enough material to allow you to begin to encounter Guru Rinpoche.
The Seven Line Prayer, which follows, is a profound practice which leads one to Guru Rinpoche. The prayer is operating at many, many levels simultaneously, from the most literal level most people notice at first to the highest levels of Dzogchen. For a wonderful discussion of the prayer, see Tulku Thondrup, Enlightened Journey: Buddhist Practice as Daily Life, "The Meaning of the Vajra Seven-Line Prayer to Guru Rinpoche", Shambhala Publications, Inc., Boston, 1995.
When practiced, the Seven Line Prayer is sung to a one or another of a variety of melodies, or chanted very quickly for accumulation. His Holiness Dudjom Rinpoche can be heard invoking Guru Rinpoche with the Seven Line Prayer on a tape available from Yeshe Nyingpo.
The Tibetan script, literal translation, and translation of the Seven Line Prayer, as well as the photo of the "looks like me" statue of Guru Rinpoche below is from
the very beautiful and wonderfully done Dudjom Tersar Ngondro, His Holiness Dudjom Rinpoche, Jigdral Yeshe Dorje, printed by Yeshe Melong for Yeshe
HUM Uddiyana country of northwest junction
HUM Uddiyana country's northwest juncture
PEMA GESAR DONGPO LA
YA TSEN CHOG GI NGO DRUB NYE
PEMA JUNG NE ZHE SU DRAG
KHOR DU KHA DRO MANG PO KOR
KHYED KYI JE SU DAG DRUB KYI
CHIN GYII LOB CHIR SHEG SU SOL
GURU PEMA SIDDHI HUM
Brief Reading List (in no particular order)
The Lotus Born: The Life Story of Padmasambhava
The Nyingma School of Tibetan Buddhism
Hidden Teachings of Tibet: An Explanation of the Terma Tradition of Tibetan Buddhism
Enlightened Journey: Buddhist Practice as Daily Life, Tulku Thondrup, Shambhala, Boston, 1995.
Advice From the Lotus-Born, A Collection of Padmasambhava's Advice to the Dakini Yeshe Tsogyal and Other Close Disciples, From the Terma treasure revelations of Nyang Ral Nyima Ozer, Guru Chowang, Pema Ledrel Tsal, Sangye Lingpa, Rigdzin Godem, and Chokgyur Lingpa; Introductory teaching by H.E. Tulku Urgyen Rinpoche, Translated by Erik Pema Kunsang, Rangjung, Yeshe Publications, Boudhanath, Arhus & Hong Kong 1994
Ngondro Commentary: Instructions for the Concise Preliminary Practices of the New Treasure of Dudjom
Tantric Practice in Nying-Ma
The Tibetan Book of Living and Dying
The Words of My Perfect Teacher, kunzang lama'i shelung
Sky Dancer: The Secret Life and Songs of the Lady Yeshe Tsogyel
Mother of Knowledge: The Enlightenment of Ye-shes mTsho-rgyal
Crystal Mirror, Volume VI