The recommended way to install all CKEditor add-ons is to create a custom build by using Online builder. To do that, click the Add to my editor button on the plugin page. When you are done, click the Build my editor button on the right side of the page to go to Online builder.
Note: This add-on is already selected to be a part of your current build.
Add-on installation instructions
If you want to add the plugin manually, you will need to:
Extract the downloaded plugin .zip into the plugins folder of your CKEditor installation. Example:
http://example.com/ckeditor/plugins/fastimage
Enable the plugin by using the extraPlugins configuration setting. Example:
I made some modifications of your plugin for my personal needs. (Resize
image, scrollbar for large image, fixbug IE, add config to set maximum size
of upload file, create lang files (en and fr)).
I have not tested it myself, but thanks anyway! :)