Great reminder from CornerTable
There are subtle differences here from Facebook, but overall, if you can navigate FB, CornerTable is the same.
If your post is set on Public/Everyone that will be the default, but if you switch your posts to "Friends only" only those who have friended you can see your posts.
Reminder: the news feed has a drop down arrow. You can choose to see ALL public posts, or only the posts by people/groups/pages you 'follow.' Conversely, to keep your posts OUT of the public posts, set your profile comments to 'friends only' and post in private groups. (Pages can choose whether or not their posts are visible to everyone or just page folowers.)