If you have a Microsoft SQL Server, Access, or SQL CE database you can create a new VistaDB database my using the Data Migration Wizard.  This will migrate the schema and data to VistaDB which is a great way to get going quickly.  You can then edit the schema using one of the other two methods below.

The integration with Visual Studio 2013 and later can be used to create and edit a VistaDB database.  This is done using the Server Explorer.  You can use a similar process to create a new database or view & edit an existing database.

1. Under the View Menu select Server Explorer to display the Server Explorer pane.
2. Right-click on Data Connections in the Server Explorer and select Add Connection...
3. In the Data Source list select VistaDB 6 File and click Continue.  This will select the VistaDB 6 ADO.NET provider. 
4. In the Add Data Source window click either Browse to find an existing database on your computer or Create to create a new database.  When you have the database options set how you want click OK.  Be sure to have the Open Mode set to a non-exclusive mode for the designer to work correctly.
5. The database will now show in the Server Explorer and you can create tables, views, functions, and stored procedures using the Visual Studio Designer. 

You can create a database outside of Visual Studio by starting Data Builder and then selecting File->New Database.  This displays the New Database dialog that lets you specify the characteristics of the database.  You can then edit this database in Data Builder. 

How To Guides

Data Builder

Visual Studio Extension