photos were posted of me in a yahoo group that I didn't even know were taken. How can I get them removed

I haven't even been able to see the pics because I can't join the group right now. So the "new yahoo appointed" moderator says. She is trying to get me to send a photo of myself with the colors inversed (which can just be inversed again back to the original) to somehow stop a hacker from intercepting the photo that she wants to use for body matching. I think that is a load of crap but I dont know much about that kind of stuff. Apparently whoever posted the pics also posted them on a pay website. When they posted the pics in the group, they have the site's logo on them. I don't know what to do. I need to know if I am being played or this pam_willis_48 is really someone working for yahoo or what. How can I get these photos removed and do I have any legal rights to bring a case against whomever it was that posted the photos in the first place? Is there any way I can find out who posted the pics? Please help me. How do I best get a hold of yahoo to find out about this person?