You may want to share a presentation or spreadsheet related to a specific session, or any other file for that matter, that's relevant to your audience.
Where on the app?
For files and content related to a session (an agenda item), you should add the content directly to the session page.
For files and content not related to a specific session, you can add those to the info page on the app.
Direct uploads or hosting externally?
Create lets you upload files directly to a session or to the info page, with some limitations on file type and size.
However, we strongly suggest you host the files on an external service with file preview functionality such as Google Drive. The main reason for this is a limitation on most Android phones, which can't preview excel files or PDF's inside the web browser. By using Google Drive for example, and linking to that file inside the app, users on Android are able to preview most files since the service provides for a file preview functionality within the page.