A Mezuzah should be affixed to the doorpost of each room in the home and place of business (including basement, attic and garage). A Mezuzah should never be placed at the entrance to a bathroom.
Procedure for affixing a Mezuzah:
Before affixing a Mezuzah to a doorpost, the following blessing should be recited:
Hebrew Transliteration: Boruch Ato A-do-nai Elo-heinu Melech Ho-olom asher kidshonu b'mitzvotov v'tzivonu likvoa Mezuzah.
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.
If more than one Mezuzah is being affixed at one time, only one blessing is recited. When affixing a Mezuzah to an archway, no blessing is recited.
The Mezuzah is affixed:
A. On the right side of the door as one enters.
B. In a slanted position with the top pointed to the inside of the room.
C. In the upper third of the doorpost height (shoulder high).
D. On the outer 3.2 inches of the doorpost width.