Picture won't load to sell item. How do I change the resolution on a Galaxy S5?

[greatitems4greatprices]

I'm trying to add an item for sell but it won't let me continue because the photo resolution isn't large enough or a high pixel. How do I can this to add the photo so I can add the item to sell? It will save it, but won't let me continue so that I can post. I am using a Galaxy S5. Thank you for your help.