In addition to the flash diffuser, you would be able to create this ample white light background using a soft box. You can build one using white styrofoam panels. Doesn't have to be pretty big, just 30x30x30 cm.
With the softbox, you can even use the flash to bounce light to the top and let the box diffuse the light around the subject.
The particular shot you posted appears to have the flash to the right of the camera generating a diffused shadow on the left. A flash diffuser was most likely used, which is a good thing in any case.
Even with the camera built-in flash, you can make a diffuser by means of a plastic semi transparent plastic or paper. Or you can buy a diffuser pretty cheap.