Hi Peter

You need the "photos and maps" section of Ancestry.

If you see in tiny writing the words "old search" near the top right of the screen, click on this, which brings up the page I always use. (I find "new search" most frustrating)

Type in John Christian, birth year 1756, in IOM, and nothing else. Then search. The tree you need from the list which appears is "Hicks and Thompson Family Tree." Cl;ick on this and you'll see the word "owner" and the username roughly in the middle of the screen. Click on this and you'll see that this person has written 11 message board posts. One of these posts has the email address of the owner.

Jean C