Help me to Build Query

Hello , 
I have two table  Table_Post  and  Table_Friend.
Table_Post have -  Postid (int) , UserID (nvarchar(50))  , Description nvarchar(800) , Shareto nvarchar(50) , Date.
Table_Friend- FID (int), UserID (nvarchar(50)),  FriendID nvarchar(50).
What I want is, when user post he set ShareTo (Friend,Family or Everybody). As per ShareTo column in post  the post should display to user. 
For example : When ShareTo is Friends , posted row only show to user friends not to all user.  When ShareTo is everybody it must show to all user's. 
It's a similar function as seen in facebook . How Can I wtite query for this one. 


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