Level CreateLevel(Autodesk.Revit.DB.Document document)
{
    // The elevation to apply to the new level
    double elevation = 20.0; 

    // Begin to create a level
    Level level = document.Create.NewLevel(elevation);
    if (null == level)
    {
        throw new Exception("Create a new level failed.");
    }

    // Change the level name
    level.Name = "New level";

    return level;
}

Private Function CreateLevel(document As Autodesk.Revit.DB.Document) As Level
    ' The elevation to apply to the new level
    Dim elevation As Double = 20.0

    ' Begin to create a level
    Dim level As Level = document.Create.NewLevel(elevation)
    If level Is Nothing Then
        Throw New Exception("Create a new level failed.")
    End If

    ' Change the level name
    level.Name = "New level"

    Return level
End Function