The short answer is that Fanpop provides an "image credit" field which every user should use to make it clear that no ownership یا rights to the تصاویر are implied سے طرف کی being گیا کیا پوسٹ here: the تصاویر still belong to <these people> (what آپ insert in the image credit field).
Do a تلاش of Fanpop (or just participate in a فورم long enough) and آپ will quickly find dozens of pages of people discussing how to properly use the image credit field. One fairly straightforward method is described in this article:
link