Good Morning Stalwart2010
Airbus has a great VNav system.
Just verify the STAR altitude constraints are in your Nav page are correct. insert your descent winds and 10 miles before your descent point (with ATC blessings of course) push nut pull the altitude selection and you are in managed descent. The reason for 10 miles is less noticeable change in engine sound, a 1,000 foot a minute descent and when the profile is met power is reduced to flight idle and all being equal you stay in the profile window.
Hope that helps