Who?It is best for the homeowner to affix the Mezuzah and say the blessings.When?The Mezuzah can be put up at any time of day or night other than Shabbat or major Jewish holidays when work is prohibited.How?The Mezuzah should be permanently affixed to the doorpost. To do this use the double-sided mounting tape. Regular scotch tape or masking tape which are temporary adhesives should not be used.The Blessing:When putting up Mezuzahs for more than one doorway in a house only say the blessing once. Prior to affixing the first Mezuzah the following should be recited: Baruch Ata A-do-nai Elo-heinu Melech Haolam Asher Kideshanu Bemitzvotav Vetzivanu Likboa Mezuzah. The Translation:Blessed are You L?rd our G?d King of the universe who has sanctified us with His commandments and commanded us to affix a Mezuzah.