Designate categories as "members-only" via 'Privacy Settings.' Assign them to users via 'Profile.'
While User Access Manager is a fine plugin, it may be cumbersome to grant access to one or more user groups upon editing each and every post.
By contrast, with this plugin, you need only consider a category as "members-only," and any content created within it will automaticaly be viewable only to those users assigned to it.
If you'd like to redirect a user to a different page upon logging in, instead of Profile, you might try WordPress Login Redirect or something similar.