How to add a box for list items?

If you want to create an option page with image upload/select fields you can use the Option Framework plugin. It is straighforward and easy to use for anyone.

If you want to add upload/select fields to a wordpress page or post use Custom Fields Creator or the more powerful plugin: Advanced Custom Fields. NB you have to buy the Repeater Field add-on to be able to use one custom field as many times as you or your client want on a page or post.