You will see the participants making gestures such as the sign of the Cross, bowing and genuflecting. These are traditional ways of worshipping with our bodies. They are not requirements of the liturgy or tests of membership. If you feel comfortable with them, use them.
As a general rule, we stand in praise, to express our worship of God with our bodies. We sit to receive instruction and listen to musical interludes, and we kneel in prayer and penitence and at certain solemn moments. We genuflect (literally 'bend the knee') when we first enter the church or our pew, and when we leave. We bow toward the altar as representing the throne of God, and genuflect more specifically toward the aumbry, a receptacle in the wall beside the altar where the Blessed Sacrament (the consecrated bread from the Mass) is reserved, in recognition of the Real Presence of Christ in the Sacrament. The presence of the Blessed Sacrament is indicated by a hanging lamp in front of the aumbry.