Each cardinal prints the name of his choice. One by one in order of seniority they approach the altar where there is a chalice with a paten on top. After each voting the ballots are burned. Special chemicals are added to make the smoke white or black. To people eagerly waiting outside, black smoke signifies an inconclusive vote.
White smoke announces that a pope has been elected.
The cardinals may elect whomever they wish, as long as the person is a baptized male. There have been occasions in the past when laymen were elected. After their election they had to be ordained priest and bishop. The one elected is asked if he accepts. The moment he accepts he is pope and, if he is a bishop, he is Bishop of Rome.