public FeatureDatasetDescription( 
   string name,
   SpatialReference spatialReference
)

// Creating a FeatureDataset named as 'Parcel_Information'

SchemaBuilder schemaBuilder = new SchemaBuilder(geodatabase);

// Create a FeatureDataset named as 'Parcel Information'
FeatureDatasetDescription featureDatasetDescription = 
  new FeatureDatasetDescription("Parcel_Information", SpatialReferences.WGS84);
schemaBuilder.Create(featureDatasetDescription);

// Build status
bool buildStatus = schemaBuilder.Build();

// Build errors
if (!buildStatus)
{
  IReadOnlyList<string> errors = schemaBuilder.ErrorMessages;
}