The "Files" section is used to sell so called e-goods: for example, e-books, software, photos, etc. I.e. downloadable products. So, it's necessary that the files should be available only after a customer purchases them successfully. More information about this feature: E-goods
In your case you need just to attach some files to product descriptions. Please, follow these steps:
- Upload the necessary files on any server. If you don't have one, you can use Dropbox: it's free
- Insert links to the files in your product descriptions using the WYSIWYG editor.