If you haven't already done so, at this point you should create a folder for your Board and put all the content you have for the Board in that same folder. Set the publishing state for the folder and its contents to private. If you do not change the publishing state, anonymous users can potentially find and access your restricted documents.

Once that is done you are ready to assign permission to work on that folder to your Board group. To do that, click on the green Sharing tab in the taskbar for your Board folder.

There are three main areas of the sharing screen:

1. Current sharing permissions for Board - Whoever created the folder in the first place will be listed here as the Owner. As you permission other users and groups, they will appear in this box.
   
2. Add sharing permissions to users - Use this box to add permissions to a single user.
   
3. Add sharing permissions to groups - Use this box to add permissions to a group. This is the box you want to permission your Board group for the Board folder.

Use the checkbox to select the Board group, then choose Manager from the Role to assign list. This will allow the Board group total control of the Board folder, but no other section of your website. If you only want your Board to view documents in the Board folder, select Member from the list instead. Push the "assign local role to selected group(s)" to finish.

Once you're all done with that, you should see the Board group appear in the first box of the Sharing screen like this:

Now all users in the Board group will have the ability to log-in, go to the Board folder, and create, edit, or view all the content contained there. In this set-up, the Board group won't be able to edit or create content anywhere else on the site.

The last thing to do would be to copy the URL of the Board folder and put it in an email to your Board members so they will know where to find their restricted access section. The Board folder won't be able to be found by a search, nor will it appear in the site navigation.