Since the mezuzah is a religious scroll, it is mandatory to say the specified blessing before hanging a Mezuzah.
The user should hold the mezuzah against the doorpost in its correct place and recite the blessing in Hebrew before permanently attaching it.
The blessing in Hebrew is: “Baruch ata Adonai, Elohanu, melech ha’olam, asher kidshanu b’mitzvotav, v’tzivanu, lik’boa mezuzah.” This translated into English as, “Blessed are You, Hashem, our God, King of the Universe, Who Sanctified us with His commandments, and has commanded us to affix a mezuzah.”