Restricting access within the WordPress admin can quickly become an intimidating place to work. When it comes to access control there are a number of really great solutions to restrict access to content on the front end, but there’s a decent learning curve when preventing logged in users from accessing various aspects of the back end.
A common need is to prevent a user or group of users from having access to a post type that is reserved for another user or group of users. WordPress has this functionality built in, but it takes some getting used to when setting it up.
This article does a great job walking you through the implementation of access control for post types within the WordPress admin.