Both required. Be as descriptive as you can — quantity, packing, product, the alleged issue, and anything else worth knowing (how the damage happened, key parts of the machine). Every caption is drafted from this line: the more you tell it, the better the captions.

Upload everything, then press ✕ on the ones you don't want in the sheet. ⇄ swaps a photo for another file. Click a photo to see it full size.