Muestra De La Cruz

My fiance and I are getting married in September. We are trying to incorporate some of our heritage into our ceremony and reception. I am part Mexican and we have chose this as one of our heritages` to honor. Does anyone know anything about the sign of the cross; the priest makes the sign of the cross and the bride and groom kiss it... Some sites mention the priest makes the sign of the cross, others say there is an actual cross. I can not find where it originated from. Most information online is short and very basic. HELP!