Hey Jay!
The word "netiquette" means the most acceptable way, or approving way of doing something.
So, by rephrasing this question in it most possible way would be the following:
Which acceptable practices should Stella follow?
I believe, and I hope this would be correct, but, seriously, the answer should be "Stella should obtain permission from her friends before posting their photographs." You would want to make sure that what you are doing in is acceptable to your parents, so even before you do so, ask your parents.
Hope this helps you!