So you need to iterate through an array and find a certain value.
First of all you should change the structure of the code.
I hope this meets your (official) knowledge in class:
Set up an object containing all the data from 1 person: name, address, street, zip, phone, etc.
Afterwards you can browse through the list of users.
Check this tutorial: http://onjava.com/pub/a/onjava/2002/02/06/jdo1.html
] for a close to your needs attempt.