1. Begin by sharing the file from one of these locations: On the detail page of the file you want to share, Click File Sharing Settings after which, Share with people. If not that, click on Sharing Settings and then click on 'People' in the Sharing Settings dialog box. Next to the file in a feed—Click More Actions | File Sharing Settings and then click on 'People' in the Sharing Settings dialog box. Next to the file on the Files home page—Click Share with people. On a file hover, Click Share File and lastly click on 'People' in the Sharing Settings dialog box.
2. On the detail page of the file you want to share—Click File Sharing Settings | Share with people. Or click Sharing Settings and then click People on the Sharing Settings dialog box.
3. Next to the file in a feed—Click More Actions | File Sharing Settings then click People on the Sharing Settings dialog box.
4. Next to the file on the Files home page—Click Share with people.
5. On a file hover Click Share File then click People on the Sharing Settings dialog box.
6. Type the name of the person you want to share the file with and click the name to select it. .
7. Choose the file permission you want them to have. By default, they have collaborator permission which lets them view, download, share, change permission, edit the file, and upload new versions. Select Viewer to give them permission to only view, download, and share files.
8. If you want to share the file with more than one person, enter more names.
9. Optionally, add information to the message that recipients will receive.
10. Click Share and Close. Recipients receive a message saying that you have shared a file with them, along with a link to the file. Lightning Experience users will receive this message as an email notification. Salesforce Classic users get a private Chatter message on their MyMessages page on the Chatter tab. However, along with it they also get an email notification if their email notifications are enabled for Chatter messages.