I don't have children, but I think if I did, I'd ease them into social media by paying them run a social media profile for a cat -- from the perspective of the cat, with no humans or PII visible, solely the cat. This would accomplish a few goals: familiarity with the tools, exposure to the annoyances of the process in a relatively safe environment, and probably dislike of the whole thing due to it being "a job" before it's a hobby or personal interest.