If you get the message that your picture was the wrong format even though it is a JPEG file, for example MyPicture.jpeg, try changing the file extension name from .JPEG to .JPG

So instead of MyPicture.jpeg

Make it MyPicture.jpg

Do this by right clicking the file and choose rename, then change the file extension by removing the "e" in .jpeg

You can also do this by opening the folder that the picture is in on your computer, clicking the file once and then going to Rename in your File menu (windows computers, macs may be similar).