// Instantiate Presentation class that represents the PPTX
Presentation pres = new Presentation();

//Write the PPTX file to disk
pres.save(dataPath + "Aspose-New-Presentation.pptx", SaveFormat.Pptx);

// Create skeletal package, including a MainPresentationPart and a SlideLayoutPart
PresentationMLPackage presentationMLPackage = PresentationMLPackage.createPackage(); 

// Need references to these parts to create a slide
// Please note that these parts *already exist* - they are
// created by createPackage() above.  See that method
// for instruction on how to create and add a part.
MainPresentationPart pp = (MainPresentationPart)presentationMLPackage.getParts().getParts().get(
        new PartName("/ppt/presentation.xml"));     
SlideLayoutPart layoutPart = (SlideLayoutPart)presentationMLPackage.getParts().getParts().get(
        new PartName("/ppt/slideLayouts/slideLayout1.xml"));

// OK, now we can create a slide
SlidePart slidePart = presentationMLPackage.createSlidePart(pp, layoutPart, 
        new PartName("/ppt/slides/slide1.xml"));

presentationMLPackage.save(new java.io.File(dataPath + "Pptx4j-New Presentation.pptx"));