Any image you paste or insert into a drawing will have a background to it.It is an image, not individual vectors or entities. Think of yourself as an artist painting a picture.Think of your computer screen as a sheet of paper and what you are trying to get it to show.You are trying to paste, with glue, a picture of something on your sheet of paper instead of drawing it with pencil.Same thing. The only way to do this is to put your image through a program which vectorizes your image into coordinate points.Then copy and paste it into your drawing.You will then have several individual entities and not a picture of those entities. Yeah, I have only had ‘transparency’ work from image program to image program.Like Paint and Adobe.For vector programs like AutoCAD there is no such luck.3D studio works but again, the shape or figure must be produced in AutoCAD as a vector shape, then imorted and exported between the two programs keeping the vector properties in tact. Source.