The Divine Liturgy of Saint John Chrysostom is the most celebrated Divine Liturgy in the Byzantine Rite. It is named after the anaphora with the same name which is its core part and it is attributed to Saint John Chrysostom, Archbishop of Constantinople in the 5th century.
If you are unfamiliar with the liturgy but would like to learn more about it, the following videos may help you come to a better understanding. The first video is a full Divine Liturgy of St. John Chrysostom celebrated in a Latin Rite church (so there is no iconostatis, or icon screen), but which uses many of the exact same tones you will hear sung at St. Thomas the Apostle. The second video is explanation of the various prayers and parts of the Divine Liturgy of St. John Chrysostom (from the Ukranian Byantine Church, but the liturgy is the same) that may help you may better participate when you visit.