Test set creation in QC using OTAClient.dll converted into Jar

I am trying to link my application with QC and create dynamic test sets through that. I am able to retrieve some QC data using OTAClient.dll. Used com4j to convert into java interfaces. Now i have a requirement of creating a NEW TEST SET in the QC test lab[Will try for existing tests first].

ITDConnection QCConnection = ClassFactory.createTDConnection();
    QCConnection.initConnection("http://server/qcbin", "division", "");
    System.out.println("Is connected: "+QCConnection.connected());
    QCConnection.connectProject("domain", "username", "password");
    System.out.println("Database entered: "+QCConnection.dbName());
    QCConnection.bugFactory().queryInterface(ITestFactory.class);
    ITestSetFactory sTestSetFactory = (QCConnection.testSetFactory()).queryInterface(ITestSetFactory.class);
    ITestSet sTestSet = (sTestSetFactory.item(14002)).queryInterface(ITestSet.class);
    System.out.println("Test details by id: "+sTestSet.checkTestInstances("testid"));

The above code is used to get the test details. Can anyone help in creation of test set? Thanks

Solution

Well thanks Plobpo. For now we used the index for root and then created a test folder. Here is the code with some additional improvements: Also includes adding release target which was one of the error we faced in the process.

ITDConnection QCConnection = ClassFactory.createTDConnection();
QCConnection.initConnection("http://nceqcwebp1/qcbin", "E_TRAVEL", "");
QCConnection.connectProject("ETVNRE", "vigupta", "Amadeus!!");
ITestSetTreeManager treeManager = QCConnection.testSetTreeManager().queryInterface(ITestSetTreeManager.class);
ITestSetFolder baseFolder = treeManager.root().queryInterface(ITestSetFolder.class);
baseFolder.addNode("Automatic Test Creation");
ITestSetFolder testSetFolder = treeManager.nodeById(baseFolder.findChildNode("Automatic Test Creation").nodeID()).queryInterface(ITestSetFolder.class);

ITestSetFactory factory = testSetFolder.testSetFactory().queryInterface(ITestSetFactory.class);
ITestSet testSet = factory.addItem(new Variant(Variant.Type.VT_NULL)).queryInterface(ITestSet.class);
testSet.name("Automatic Test Set");
testSet.status("Open");

testSet.field("CY_USER_04", "no schema used");
testSet.field("CY_USER_07", "Non-regression");
testSet.post();
testSet.unLockObject();