Spanning Backup offers the ability to select where you would like your backed up Salesforce data stored: The United States or Europe. This selection takes place after your installation of Spanning Backup, when you log into Spanning for the first time, and once selected, cannot be changed.
After you install Spanning Backup and complete all of the post-installation configuration steps, when you log into your application for the first time, you will be presented with the option to choose the North American data center or the European data center, as shown below:
This is the final step listed in the post-installation configuration steps in the Spanning Backup for Salesforce installation guide, which can be seen here:
Salesforce Installation Guide