CANNES, France (AP) — The news that Molly Manning Walker’s first feature film “How to Have Sex” had gotten into the Cannes Film Festival set off perhaps the most surreal six weeks of the 29-year-old’s life. A headlong sprint to finish the film didn’t stop until 48 hours before Walker stepped into Cannes. No festival can launch a new voice in cinema quite like Cannes. This year, Walker is among the most promising new filmmakers in at the festival. “How to Have Sex” is a vivid, assured drama about a British teenager who takes a trip to Greece hoping to lose her virginity. On Friday, the film won the top prize in the festival’s Un Certain Regard section.