Connecting to a file store through a VPN

For an assignment, I have to build a service for the "road warriors" of a theoretical company. Basically, they need remote access to a file store or share that has to go through a VPN in the cloud. I've built an openVPN server in AWS, but I am not certain about the next step. My teacher vaguely suggested just having an HTTP server with a directory for the remote users to access through the VPN. So I was thinking of launching another EC2 instance and setting it up as an Apache web server, and getting the VPN to route to that. The question is, how do I get the users to be able to upload and download files to and from the directory on the web server?