verona to zurich

Your route will be Verona-Milano-Zuerich. You can book both legs on trenitalia.com. Or since it's too late to get discount fares, you could simply buy your tickets at the station in Verona.

JR, I agree with Tim I'm assuming you mean Wednesday (tomorrow), so it's too late to get any discounted fares. The easiest solution would be to just buy the tickets at Verona Porta Nuova. As I recall, the ticket windows are to the left as you enter the main doors. The fastest train appears to be a departure at 09:32, arriving Zürich at 14:51 (time 5H:19M, 1 change at Milano Centrale, reservations compulsory on both legs). One other advantage of that particular trip is that your layover in Milan is only 15 minutes. Happy travels!

If, as Ken says, you only have 15 minutes at Milano Centrale I'd advise you to pick up your feet. You have to go right to the front of the train you came in on, then walk to the next train and walk from the back of that train until you find the seats you are reserved in. You could just get on at the back if time is very tight and walk through but that is no fun if you have luggage.