There is a special attribute in the 'http://www.w3.org/2001/XMLSchema-instance' namespace called 'schemaLocation'.

The value is a list of whitespace separated namespace name and locations.

For example, the order document:

<orders xmlns='urn:publicid:IDN+cde.berkeley.edu:schemas:examples:200402:us'
  xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'
  xsi:schemaLocation='urn:publicid:IDN+cde.berkeley.edu:schemas:examples:200402:us pizza-order.xsd'>
...
</orders>

This maps the namespace name of 'orders' to the local schema document 'pizza-order.xsd'.

The syntax is horrible and if you move the document the location could break.

We'll learn better ways next time... but try this in Netbeans.