To share a file while in an application i.e. Word, Excel, PowerPoint, follow these instructions.
1. Open the document.
2. Go to File and save it to your OneDrive. It cannot be shared unless it is in your OneDrive.
3. Once it is saved in your OneDrive, go to File -> Share -> Share with People > click Share with People button.
4. Over to the right of the screen is where you will start sharing.
5. Type the user you would like to share with.
6. Select if you just want the user to view the file, or if they can edit the file.
7. Select if you want the user to ask to share the changes, always share the changes, or never share the changes.
8. Click Share.
9. Now the document is shared with the permissions you have specified.