I have ordered a package and usps says it has arrived in yo,ny?

Class: First-Class Mail®
Service(s): Delivery Confirmation™
Status: Arrival at Unit
stated here
Your item arrived at 9:19 AM on May 22, 2009 in YONKERS, NY 10701. Information, if available, is updated periodically throughout the day. Please check again later.
DOES THIS MEAN THAT THEY TRIED TO DELIVER IT AND IF SO HOW DO I GET MY PACKAGE
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The mail truck has dropped off your package at the mail hub in Yonkers, if it said delivery attempt or being delivered then I'd look into it.
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It could just mean that it has arrived at a "hub" branch where it will get loaded unto another truck to continue on its trip to you. If the package is not late yet, give it about 24 hours and see if the location of your package changed again. If it has not changed, then contact someone. I bet it is just changing trucks to get to you.
edit: Contact the company that is delivering the package first. Then the company that actually sent it if needed.