Adding Images to items

I have just added an app 'discogs' but when it comes to adding an image the options the search engine brings up are way out. I've also had this problem when tried to add a book or music album. Can't remember what the items were it was ages ago but because I couldn't add the correct image I didn't bother adding the items. Sometimes the images provided when wanting to add to an item are seemingly random as they don't have any discernible relation to the item in question.