enabling plugin

I am trying to configure the CKEditor Image Browser plugin, 

firstly where do I add this?  

Enable the plugin by adding it to extraPlugins and specify the imageBrowser_listUrl parameter:

CKEDITOR.replace('textareaId', {
        "extraPlugins": "imagebrowser",
        "imageBrowser_listUrl": "/path/to/images_list.json"
});

https://github.com/spantaleev/ckeditor-imagebrowser#usage