The glorious Tantra King who cut off all secrets - Der glorreiche Tantrakönig, der alle Geheimnisse abgeschnitten hat. English an German Text, Vocabulary and Remarks

The text is dates back to the 11th century. It is from the indian pandit Gayadhara and the tibetan translator Drokmi. This text contains meditation practices from Tibetan Buddhism. Tibetan Buddhism uses linguistic and ritual symbols that are not accessible without instruction. Texts and instructions cannot therefore be understood without appropriate instruction. Tantric texts like these require years of engagement with Buddhist content.
Buddhist teachings are divided into the General Paths and the Higher Paths on the Vajrayana Path. For tantric texts like this one should already have a deep knowledge of Tibetan Buddhism. They presuppose the teachings from the general paths. In addition, one should be familiar with Deity Yoga and have received at least one initiation into the Supreme Yogatantra from a qualified teacher. You should also have contact persons as well as a qualified teacher to whom you can ask questions.
These can be found in Tibetan centers of all schools.