Basic problem inserting image into div tag

So I’ve set my css stylesheet and set-up my page with a set dimension.
The problem comes when I insert an image that is the same size of a div. Instead of forming around it, it goes out of the borders.
Is there a way to make the image fit the exact size of the div?

Damn, all it accomplished is to move all my other shit around

FUCK WHAT THE FUCK IS UP WITH THIS WHITE SPACE THAT KEEPS POPPING UP FROM ANYWHERE