The picture must be a .png, .jpg or .gif file type and uploaded in the control panel.
The recommended file size less is than 5MB. A maximum file of 10 files with max total size that 100MB can be uploaded is 20 MB and your internet speed must be fast enough to complete the upload within 60 seconds, if you have problems uploading please try a smaller fileat once.
Upload the pictures you want to use.