HELP PLEASE- Superimpose two images in a QPixmap

[wysota]

Should I use something else for transparency?

A transparent image that you render on the pixmap (be it transparent or not). I don't know what sizes your jpeg images have but assuming their size is somewhere close to 500x500, they will most probably cover the whole area of the pixmap so it doesn't matter if you "fill the pixmap with transparency" or not if you then draw a non-transparent image over it.