There are 3 main steps involved in sharing your dashboard.
Share the Filebox (click here to see how)
Set the Permissions Filtering for the file (and versions) for viewing on the BI (click here to see how).
Click on the dashboard that you would like to share; it will become activated, and you will see the widgets.
A small edit icon will appear near the dashboard name.
Click it, and select "share".
A list of users who have been shared to the Filebox will populate. Click the Green plus sign to add them to the dashboard.
Once the user has been successfully added, they will appear in the "dashboard shared with users" panel. They can easily be removed by clicking the red minus sign next to their name.