First thing you need to do is install and activate the WP JV Post Reading Groups and upon activation go to Settings > Reading to create reading groups. Start by entering a name for your reading group and then click on “Add new reading group” button. Once you are satisfied, it is time to add users into your reading groups. Go to the Users page in your WordPress admin area and edit the user you want to add to a group. You will find the WP JV Reading Groups section towards the bottom of the screen. Check the box next to the user group where you want to add this user and you can add a user into multiple groups. Click on update user button when you are done.
Now that you have setup your users group, take a how to privately share posts with a specific user group. Create a new post or editing an existing one and you will notice the new WP JV Reading groups meta box. Click the checkbox next to the group name you want to share the post with. Then, under the Publish meta box click on the Edit link next to Visibility, and set your post to private. And that’s all.
There are screenshots on how to do it provided by WPBeginner, kindly check this.
