To import a file that contains definitions for use in Blue Integrator (in XML format), right-click on the root of the Blue Integrator Explorer window and select Import… from the pop-up menu:

When you click on Import…, you will see the usual file browser window.  Navigate to the file to be imported, then either double-click on the file or highlight it and select Open.

The contents of the file will then be imported into Blue Integrator.  If an error occurs (most likely due to improper formatting of the file), an error dialog will be displayed.