Does one need to pay for a membership to add the personal data that I see on several members? I see where it could be added but it wont let me add anything?

No, you do not need to pay for it. I have only gotten it to work when I am logged in to my computer. When I use my computer, in the upper part where the black bar is with your name and profile picture, click the down arrow. Then click 'my surgery' and it will allow you to update the details of your surgery once you are on that page. If you want to add weight, etc. click on 'progress' off to the left. I hope this helps.

there's no membership on this site that I'm aware of. I think you might have to be on a regular computer (desktop or laptop) to edit that. I was looking earlier today for someone else on the phone app, and I couldn't find where you could edit those fields. I can definitely get to it (and edit it) on my laptop, though