Collection<DbfColumn> dbfColumns = new Collection<DbfColumn>();
            DbfColumn column1 = new DbfColumn("id", DbfColumnType.String, 20, 0);
            DbfColumn column2 = new DbfColumn("name", DbfColumnType.String, 20, 0);
            dbfColumns.Add(column1);
            dbfColumns.Add(column2);

            /////////////// createshapefile and add a polygon into .shp file and two fields into .dbf file
            ShapeFileFeatureLayer.CreateShapeFile(ShapeFileType.Polygon, "../A.SHP", dbfColumns);

            ShapeFileFeatureLayer shpLayer = new ShapeFileFeatureLayer("../A.SHP", ShapeFileReadWriteMode.ReadWrite);
            PolygonShape polygonToAdd = new PolygonShape("POLYGON ((30 10, 10 20, 20 40, 40 40, 30 10))");
            Dictionary<string, string> dbfValues = new Dictionary<string, string>();
            dbfValues.Add("id", "1");
            dbfValues.Add("name", "polygon1");

            shpLayer.FeatureSource.Open();
            shpLayer.FeatureSource.BeginTransaction();
            shpLayer.FeatureSource.AddFeature(polygonToAdd, dbfValues);
            shpLayer.FeatureSource.CommitTransaction();
            shpLayer.Close();


            /////////////add a column to a dbf file 
            ShapeFileFeatureSource shpFeatureSource = new ShapeFileFeatureSource("../A.SHP", ShapeFileReadWriteMode.ReadWrite);
            shpFeatureSource.Open();
            shpFeatureSource.AddColumnString("newcolumn", 20);
            shpFeatureSource.RefreshColumns();
            Collection<Feature> features = shpFeatureSource.GetAllFeatures(ReturningColumnsType.AllColumns);
            shpFeatureSource.Close();

            Feature featureToChange = features[0];

            ////// change a field value
            GeoDbf dbfEdit = new GeoDbf("../A.dbf", DbfReadWriteMode.ReadWrite);
            dbfEdit.Open();
            dbfEdit.UpdateColumnName(2, "newName");
            dbfEdit.WriteField(Convert.ToInt32(featureToChange.Id), "newName", "newPolygon");
            dbfEdit.Close();