preview the slideshow

Premiere Elements built the slide show. Since your music file is already on the Timeline, you can preview after adding the pictures. Click Undo if you don't like the result, and immediately experiment with new picture and transition durations.

Note that the song is longer than the slide show, which is OK. In Chapter 6, you'll add a title before the slideshow, and at least one title ("The End") after the slideshow. These will consume some of the extra music, and you'll delete the rest and fade to silence in Chapter 7.