When you marry, what is the procedure according to Islam. Here in Canada, the legal age is 18. Are we allowed to marry before that age, even in Canada. And in Islam, is it allowed to marry non-Muslim women?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

The conditions of a valid marriage in Islam are made clear in the Fatwa 83629                                                               As for marrying while young (less than 18) it is lawful. The Prophet (Sallallahu Alaihi wa Sallam), for instance, married Ayisha (RAA) while she was less than 10 years old. For more details about this marriage, read Fatwa ">84343. On the other hand, one should not abide by any rules that do not conform to Sharia'a. As for marrying a non-Muslim, it is lawful if she is from the people of scripture (Christians and Jews) and if she is chaste. For more details about this subject, please read 82067.
We would like here to call your attention to the fact that the slave Muslim woman is better than any disbelieving woman. Allah says: {……And indeed a slave woman who believes is better than a (free) Mushrikah (idolatress, etc.), even though she pleases you. And give not (your daughters) in marriage to Al-Mushrikûn till they believe (in Allâh Alone) and verily, a believing slave is better than a (free) Mushrik (idolater, etc.), even though he pleases you. Those (Al-Mushrikûn) invite you to the Fire, but Allâh invites (you) to Paradise} [2:221].
Allah knows best.