The Mezuzah is a unique piece of Judaica, like no other. A symbol and reminder of our connection with G-d every single time we pass through the door of a Jewish home or business, this wonderful item is made up of a Mezuzah scroll and a Mezuzah case. Upon the scroll are the words of the Shema, and one of G-ds many names on the outside. This scroll is rolled up and placed into a case for safekeeping, which is then affixed to the doorposts of every door in a Jewish establishment or home with the exception of the bathrooms.
Connected on the right side of the doorway as you enter, it should hang at a slight angle, the top attached towards the inner side of the doorpost and the bottom attached near the outer side of the post, such that the mezuzah is pointing
into the room with the top. The Mezuzah isn’t hung just anywhere on the doorpost, either. It is hung two-thirds of the way up, at shoulder level. When it is a taller than average doorway, the Mezuzah is still hung at shoulder level. In doorways between rooms, the mezuzah is affixed on the right side when entering the doorway in the direction the door moves, as in, when pushing open the door as opposed to pulling it. When the doorposts are too narrow to hold a Mezuzah, a groove is cut for it, or it is attached within 3 inches of the door on the inside. This is also true if you fear your Mezuzah will be defaced if left outside.
It is a great practice to teach your children to kiss the mezuzah as you pass with them through the door, lifting them to give it a kiss or blow it a kiss.
The affixing of the Mezuzah in a new home’s doorway has a wonderful ceremony attached. The whole household and sometimes guests gather around, and the homeowner (or his delegate, if he does not know how to bless) holds the Mezuzah in place, says the Mezuzah blessing and recites the Shehechiyanu blessing over the new home, and then hammers it in.
The Mezuzah Blessing goes like this:
ברוך אתה ה` אלוקינו מלך העולם אשר קדשנו במצותיו וצונו לקבע מזוזה
Baruch Ata A-do-nai Elo-heinu Melech Haolam asher kideshanu bemitzvotav vetzivanu likboa mezuza.
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.
Shehechiyanu goes like this:
ברוך אתה ה` אלוקינו מלך העולם שהחינו וקימנו והגיענו לזמן הזה
Baruch Ata A-do-nai Elo-heinu Melech Haolam shehecheeyanu v’kiyimanu vi’higiyanu lazman hazeh.
Blessed are You, L-rd our G‑d, King of the Universe, who has granted us life, sustained us and enabled us to reach this occasion.
When It is not the first Mezuzah of the new home, Shehechiyanu is not said. After saying the blessings, everyone keeps quiet while any necessary Mezuzahs are nailed in. Only one blessing is said for any number of Mezuzahs the home needs put in.
The suggestion is to nail them in, for permanence, an important component of Mezuzah affixing. However if for whatever reason, nails are not possible, other measures may be used.