I am developing app which add contact info to android contact list .to How to add postal address to contacts in android programmatically ?
Postal address are stored like all the other info in the DATA table with a
MIMEtype == ContactsContract.CommonDataKinds.StructuredPostal.CONTENT_ITEM_TYPE
Please google ContactsContract.CommonDataKinds.StructuredPostal
to find all the info.
If you need to know how to edit a contact in general I would suggest you to have a look to the SampleSyncAdapter in the Android SDK. It is a sync adapter so you don't need to study everything but updateContact in ContactManager is a good point to start with.