[youtube https://www.youtube.com/watch?v=azETGMS16pQ?rel=0]
Sharing documents is easy. You must UNLEARN the habit of storing everything in the local My Documents folder and store things in SharePoint.
If you use Office 365, this should be done using OneDrive. (What is OneDrive?)
These videos were created three years back. That is why they use older logos and screenshots. The concepts, however, are unchanged and still valid as of now (Feb 2015).