Finding resources
When you upload an image you are asked to provide a license.
What you choose depends on the licence that your image has.
If you are using an image of your own choose the licence you want. I favour Attribution. if someone wants to use my image that's cool. Just acknowledge me.
If you have used an image that has a CC license then you must add that licence. It's not necessary to add the image but you should acknowledge it, name the licence and add the website.
Like this