The Tibetans are for the generation and dissemination of micro releases of Kundalini throughout the body. Allowing the body to adjust and allowing health benefits to be kindled. They are directed to the first five chakras. Each Tibetan is designed to assist the energy to climb higher and higher in a bottom to top fashion.
Start slow with no more than 6 repetitions for each Tibetan. Gradually increase to up to 21 repetitions but no more.
For additional guidance on how the 5 Tibetan Rites should be performed Mary Kurus has an excellent article based on The Ancient Secret of the Fountain of Youth written by Peter Kelder, or alternatively LifeEvents provides a handy summary with animated pictures of the poses.