Saving the image to a session from the login and using that to show the image is fine.
Alternatively, the login saves the User ID to a session, you could create a recordset that filters the ID column of the users table on the user ID session that is saved to retroeve the image name.
as for the details page, the details link should pass the ID as a URL variable.
On the details page, you create a recordset that filters the ID on the URL variable to retrieve the information for the detail record.
See the Database starter kit tutorial for details on creating this, it is written for a products table, but the concept is the same: