How to: Change a Picture's Z-Order and Text Wrapping
The following code snippet uses the Shape.ZOrder property to position an image behind the specified drawing object and sets the Shape.TextWrapping property to set the image behind the text of the document.
Note
A complete sample project is available at https://github.com/DevExpress-Examples/wpf-richedit-document-api-t213968.
document.LoadDocument("Documents//Grimm.docx", DevExpress.XtraRichEdit.DocumentFormat.OpenXml);
Shape myPicture = document.Shapes[1];
myPicture.VerticalAlignment = ShapeVerticalAlignment.Top;
myPicture.ZOrder = document.Shapes[0].ZOrder - 1;
myPicture.TextWrapping = TextWrappingType.BehindText;