The day of Epiphany, January 6, is the day the church celebrates the revelation of Christ to all nations as represented by the magi who come to worship Jesus. In the Orthodox traditions, Epiphany is the observation of the Baptism of Jesus.
The church calendar recognizes the season of Epiphany from January 6 until the last Sunday before Ash Wednesday which is celebrated as the Transfiguration of our Lord. Sundays are known as the First Sunday after Epiphany, Second Sunday, and so on.
The color used on the Sundays after Epiphany is green.
The General Board of Discipleship has resources at this link.