Portrait Jpegs

[Bob6C15]

Trying to save photos (jpegs) for use in Windows wallpaper (the slideshow option).  Portrait oriented jpegs only display the center of the jpeg.  Is there a way to resize the photo so the entire photo will show?  I am a neophyte user by the way.

[Peru Bob]

Make the canvas larger:

Image > Resize > Canvas size from the Editor menu.