In the solemnization of marriage no particular form is required except that the parties shall assent or declare in the presence of each other and the person solemnizing the marriage and in the presence of at least two competent witnesses that they take each other to be husband and wife. A competent witness for this purpose is a person of sound mind capable of understanding the seriousness of the ceremony. At the time of the ceremony, the person solemnizing the marriage shall complete the certification on the original marriage certificate. The person solemnizing the marriage and the two attending witnesses shall sign the original marriage certificate and the necessary copies.