dear rstrats...
Passover begins on the 14th at sundown and the feast of unleavened bread starts at sundown on the 15th. The feast of unleavened bread lasts 7 days and the first and last days are called sabbaths. They can fall on any day of the week. If passover started on wednesday evening, the next evening (thursday) would be the beginning of the feast of unleavened bread & a sabbath. Friday evening would start the regular weekly sabbath (2nd night) saturday evening: weekly sabbath ends (3rd night) saturday evening until sunday evening is the 1st day of the week according to the jewish calendar (resurrection "day").
Jesus would have had to be tried and crucified between the passover meal on wednesday evening and removed to the tomb before the evening of the 15th.(1st night)