Adding Pictures to a Chapter

I've create a map for my fiction (yay!) and now I want to add it to the end of a chapter, just because. However, the 'add image' tool isn't very intuitive. Do I need to upload an image directly from the internet (google images or elsewhere)? I tried dragging and dropping, and that doesn't work. Is it because it's a png, and I need some other file format?

How can I just take my picture from my file folders and put them in the chapter? 

Thanks in advance!