Found via Google.
"Open the Settings application a go to to General -> Siri. In that settings page there's a field that says My Info -- click on that field and select your contact entry from your Contacts application.
Now when you ask Siri to find a route home for you, it will use the home address saved in the contact that you said was you.
You can add other places to this contact card and Siri will recognize them like work. You can also set up relationships in this card. For example: if you create a contact card for your spouse, you can in your contact card link to this other card as a relationship with type spouse or wife or husband. Now when you Siri to "Call my spouse" it will use this relationship in your contact card to determine who your "spouse" is and what numbers are available to be called.
