Exporting data from VistaDB to any application can be accomplished in a number of ways.  In most cases the best way to export and import data with your own application is to write your own implementation in .NET, typically using serialized DataSets or objects.  In addition, here are some approaches that can be done using common tooling for developers.

Data Builder - Export XML

Save the data into XML with data and relationships. Use Data Builder select XML Import and Export from the File menu to export the data (and optionally the schema) to a local file.  For more information see DataBuilder ExportXml

SQL Server Integration Services (SSIS)

Import data into SQL Server using the DTS Wizard. The DTS Wizard for non Microsoft databases can only load one table at a time for Express users, but full SQL Server users can build up migration scripts and execute them all at once.

ADO.NET Provider Factory

Any application that can load an ADO.NET Provider factory should be able to load and use the VistaDB Provider Factory.  See ADO.NET Factory Objects in your app.config or web.config for how to set up the provider factory.