FOR COMPUTER TECHIE EYES ONLY

Sorry about this, but the only way I seem to be able to get this photo up on the Profile bit (top left) is to put it on a blog entry (to put it online, in order to give the jpg name to the profile-edit bit). You used to be able to do this temporarily, and then delete the posting with it on, and it would remain as the profile image - but under the newer-fangled Google-owned version of Blogger this no longer seems to happen. Can anyone out there talk me through solving this problem please? (Naturally the Blogger Help section is no help at all.)