Solution for changing dir where are will be IMG stored

I am newbie, who's working on little project about local bands. There will be form for adding img, which will be used for gallery. Every band has own gallery. So my idea is: http://ift.tt/2i3cWWi. And page with text will be: http://ift.tt/2j1wc4M. But I am not sure, how should look script, which allow change path to save img. Becouse person, who can upload these img will have got from, where will be , where he could choose band. So, is there any solution for this. Thanks