The tradition of Gnosis has taken on innumerable forms throughout the centuries; one of those forms is popularly assumed to be the totality of Gnosis: a diverse and often conflicting collection of traditions loosely centered around the Mediterranean Sea many centuries ago. Here are some example writings from that time and place, and an illustration of the true nature of the Gnostic teachings, which is far more ancient and wide-spread than humanity realizes, and is very much alive today.
This website has many articles and lectures that explain the most famous and widely known Gnostic scriptures: the books of Moses and the Gospels of Christianity. Kabbalah of Genesis reveals many of the mysteries of the book of Genesis.
The most important Gnostic scripture is The Pistis Sophia, about which Samael Aun Weor wrote several hundred pages of commentary.
To learn about the Gnostic teachings in the book of Genesis, read The Secret Teachings of Moses.