Having created a blog post in wp-admin using my Administrator credentials, how do I change the author to another User?
Separately, where does a User who is designated as Contributor log in to author a post more directly?
In Posts > All Posts, you can select “Quick Edit” beneath the post(s) you wish to change, then select a different author. Be sure to select the “Update” button to save your changes.
You can also select multiple posts, then use the Bulk Edit feature to change several posts at once.
This is covered in our WordPress 101 course, in the video tutorial titled, “Edit Existing Posts”.
To your second question, ALL users log in at the same address. e.g., add ‘/wp-admin’ to the end of your site’s URL.
This is covered in our video tutorial on “Adding New Users”.
Hope this helps!