SharePoint 2013 Discussion items "visibility" depending on permession for specific groups and users

Hello,

I have a blank site in SharePoint 2013 in which i activated `CommunityFeature` and i created a discussion board app which is displayed in a web part.

Now, i want to be able to change the discussion visibility ... E.g. when i click on new discussion i want to have a people picker that allows me to choose people or groups that are allowed to see and reply for that discussion...

How can this be made? can anyone help me please?