Tantra is an ancient philosophy and spiritual science. It is not so much about sex; rather Tantra is about embracing universal shakti energies. For all energy is fundamentally sexual.
Tantra takes in to account the dark and the light, accepting all. We understand the world made of complementary energies: Shiva and Shakti; man and woman. While Shiva signifies the pure awareness we might hope to achieve or glipse, in meditation, shakti is illusion or "maya," everything in the manifested world. But instead of seeing this as negative, through tantra we explore ourselves physically through yoga, dance and meditation practices to gain awareness on deeper levels.
What to expect from a tantra class?
Tantra practices, such as a Tantra yoga class, will most likely be focussed on becoming more aware of oneself. Through pranayama (breathwork), meditation and physical yoga asana (posture), we become more aware of our subtler energies, relating to chakras and universal energies. In a yoga class, you can expect to stay in postures longer, going deeper through the breathe to discover new depth and inner peace in your practice.