This piece of code should work on an established sesision and demonstrates a basic get and put document operation.

Hope this helps.

try {
        root = (Document) session.newRequest("Document.Fetch").set( "value", "/default-domain/workspaces").execute();
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
            DocumentService documentService = new DocumentService(session);

    try {
        OperationRequest request = session.newRequest("Document.Create");
        request.setInput(root);
        request.set("type", "File");
        request.set("name", "yourFileName");
        request.set("properties", "dc:title=yourTitle");
        request.execute();
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }