First you have to be registered and logged in here which should show you this:
Then scroll ALL the way to the bottom and find the "members" link
And here's where it starts to get a bit less clean.
IF the user is registered here AND IF you can find the name.
(We asked all users to use a standard configuration of first name, last name or first initial last name but for their reasons, some folks didn't want to do that, e.g., privacy concerns, "I've always been known as RosySweetCheeks on forums" and any number of other reasons.)
Whatever login they're using will be listed alphabetically, so you can find JD Walton.
Click on the login name in the left hand column which will bring you to this (Note that I've blocked the personal info in this screen.):
This should bring you to a fairly standard text entry screen to send the email (including sending a copy to yourself.) You won't see their email address -- this was in response to a number of shipmates who prefer the added assurance that their email won't be made available to spammers or other folks with bad intentions.
What happens next depends on other things. Does your recipient have a current email listed on this forum? Is it one they still check? If so, they will receive an email from the forum.
A less than perfect combination of making contact possible while protecting privacy.