Article Permissions

I want to set up users to have selective edit access to only particular articles, but I see I can only create groups that have broader authority. How can I drill down the permissions so that users can edit only particular articles?

I tried many variations of changing the permissions in Global Configuration, but it didn't work.

Thank in advance for your help!

Make sure you are familiar enough with ACL docs.joomla.org/Access_Control_List/1.6-2.5/Tutorial

This is not related to Joomla template.