Happy Theophany!

Troparion - When You, O Lord were baptized in the Jordan, the worship of the Trinity was made manifest. For the voice of the Father bore witness to You and called You His beloved Son. And the Spirit, in the form of a dove, confirmed the truthfulness of His word. O Christ, our God, You have revealed Yourself and have enlightened the world, glory to You!

Kontakion - Today You have shown forth to the world, O Lord, and the light of Your countenance has been marked on us. Knowing You, we sing Your praises. You have come and revealed Yourself, O unapproachable Light.

(from www.oca.org)

The Antiochian Archdiocese provides an interactive explanation of the icon of Theophany, which I highly recommend.