If there is a document, maybe an event pack, that you want to provide to your Attendees then you can upload them here. There are "fair useage" limits applied to this area that normally you will not hit however you may receive a warning or error if you are uploading and deleting files too regularly; this is purely based on the cost of hosting and transfer.
If you select a file to only be visible to Paid Attendees this only impacts where the file is available for download via this site; the link itself does not validate the status of the person downloading.
These are the standard documents you probably want to think about providing for download by your Attendees. Eventually tourn.ee will allow you auto-generate these from the data you have already entered.