//Add data
for (var col = 1; col < 6; col++) {
    for (var row = 2; row < 11; row++) {
        activeSheet.setValue(row, col, row + col);
    }
}

var sTable = activeSheet.tables.add("table1", 1, 1, 10, 5, GC.Spread.Sheets.Tables.TableTheme.medium2);
var drange = sTable.dataRange();
alert(drange.row);