builder.insertImage(dataPath + "background.jpg");

builder.insertImage(dataPath + "bg.jpg",
        RelativeHorizontalPosition.MARGIN,
        100,
        RelativeVerticalPosition.MARGIN,
        200,
        200,
        100,
        WrapType.SQUARE);

WordprocessingMLPackage wordMLPackage = WordprocessingMLPackage.createPackage();

// The image to add
File file = new File(dataPath + "java_logo.png" );

// Our utility method wants that as a byte array
java.io.InputStream is = new java.io.FileInputStream(file );
long length = file.length();    
// You cannot create an array using a long type.
// It needs to be an int type.
if (length > Integer.MAX_VALUE) {
    System.out.println("File too large!!");
}
byte[] bytes = new byte[(int)length];
int offset = 0;
int numRead = 0;
while (offset < bytes.length
       && (numRead=is.read(bytes, offset, bytes.length-offset)) >= 0) {
    offset += numRead;
}
// Ensure all the bytes have been read in
if (offset < bytes.length) {
    System.out.println("Could not completely read file "+file.getName());
}
is.close();

String filenameHint = null;
String altText = null;
int id1 = 0;
int id2 = 1;

// Image 1: no width specified
org.docx4j.wml.P p = newImage( wordMLPackage, bytes, 
        filenameHint, altText, 
        id1, id2 );
wordMLPackage.getMainDocumentPart().addObject(p);

// Image 2: width 3000
org.docx4j.wml.P p2 = newImage( wordMLPackage, bytes, 
        filenameHint, altText, 
        id1, id2, 3000 );
wordMLPackage.getMainDocumentPart().addObject(p2);

// Image 3: width 6000
org.docx4j.wml.P p3 = newImage( wordMLPackage, bytes, 
        filenameHint, altText, 
        id1, id2, 6000 );
wordMLPackage.getMainDocumentPart().addObject(p3);


// Now save it 
wordMLPackage.save(new java.io.File(dataPath + "OUT_AddImage.docx") );