for simple upload image, install plugin from
https://packagist.org/josegonzalez/cakephp-upload
then installed via composer
composer require josegonzalez/cakephp-upload
then you can read full documentation in
http://josediazgonzalez.com/2015/12/05/uploading-files-and-images/
include tutorial online storage services
-Amazon Web Service
-Windows Azure
-DropBox