Hi.
I always prepare photos in the program called Gimp, (it's free) from there I can produce the end result ready for Scribus. But your PSD format is often used in working with layers. If that is the case you might want to flatten the layers.
However, I suspect that the format is not your problem, having just started using Scribus. To get a photo into your work you need to make a graphics frame. Then get the photo into the size you need. Don't forget that you also need it to be sufficient dot per inch. (dpi) that is 300 dpi. the easiest way find it to first open the file in Inkscape and convert it to a svg format, that is a vector one.
Hope all this helps.
Wena D. Parry.
South Wales, U.K.