Greetings and blessings!
In response to the notification about your entry to the age of mitzvos:
May it be G-d's will that from being "thirteen, and obliged to observe the mitzvos," you will grow to be fifteen, and so on, [at each age fulfilling your obligations] as set out in the Mishnah (Avos, ch. 5). May you become increasingly studious and conscientious in your study of the Torah, in the revealed teachings of the Torah and likewise in the teachings of Chassidus, and may you observe the mitzvos precisely and beautifully. And may G-d grant you success in your endeavors to become a chassid, a G-d-fearing Jew, and a scholar.
[The Rebbe's signature]