Google Drive is a great way to share files with one another. It will support any file type. There are advantages to using Google's own file, such as simultanious viewing and editing. But you can also just use this as a place to store and share files.
All you need is a Google account and you are ready to go.
Wikis are also great collaborative spaces for file sharing, project managament and more. Check out PBWorks. You can create a private wiki and invite only your team members.
Invite your classmates to share documents!
Invite your classmates to a shared wiki