Translation of estéril

The picture I sent yesterday was taken on the first evening. And this morning the email bounced back. The user has already uploaded 3 different pictures of himself, all with the same facial expressions.
It is called Facebook viral marketing. I'm 62 and it's somewhat mystifying, but my two boys are using it continuously. What I'm a bit afraid of is the personal information they send to everybody. It has no privacy.
I would be glad if you can tell me more about the United States, of course in German! Maybe we can talk again when you're back at home, what do you think? That would be a good practice, wouldn't it.