All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
Engagement is to ask a woman for marriage or to ask her guardian to marry her, its importance is that it is a reason for marriage to actually take place. The marriage does not take place unless the concerned parties agree; and this of course happens only after the engagement.
Engagement does not have any special ceremony, and it is sufficient for a person who proposes to marry the woman, or for his agent to ask the guardian of the woman to marry her off to him; if the guardian agrees and the woman agrees then the engagement has taken place.
Allaah Knows best.