To personalize your profile, simply browse to it and click on the ellipsis ('…' next to the 'Set Online Status' button. Click it and
choose 'Change Cover Image'. This will bring up a list of screenshots
currently saved on your PS4. Choose one, and then resize it using the
analogue sticks. Once you're done, the picture will be uploaded to
Sony's servers, and your profile will be updated to see it.If you want to use a custom image, then you could always use
the PS4's internet browser to search for a picture,
and use the Share button
to save it on your hard drive. Just remember to keep it clean and
inoffensive – we imagine that you could get banned if you start
uploading images of scantily clad ladies. Illegally cute kittens should
be okay, though.