Once a ship's sea trials are successfully completed plans for the actual commissioning ceremony will take shape. Depending on the naval traditions of the nation in question, the commissioning ceremony may be an elaborately planned event with guests, the ship's future crew, and other persons of interest in attendance, or the nation in question may forgo a ceremony and instead administratively place the ship in commission.
At a minimum, on the day on which the ship in question is to be commissioned the crew will report for duty aboard the ship and the commanding officer will read through the orders given for the ship and its personnel. If the ship's ceremony is a public affair the Captain may make a speech to the audience, along with other VIPs as the ceremony dictates. Religious ceremonies, such as blessing the ship or the singing of traditional hymns or songs, may also occur.
Once a ship has been commissioned its final step toward becoming an active unit of the navy it now serves is to report to its home port and officially load or accept any remaining equipment (such as munitions).
Information Courtesy of Wikipedia