You're right, the tiny box indicates a broken path.
There are reasons to have an absolute path and other reasons to have a relative path.
absolute
<img src="https://pathToMyDomain.com/images/thisIsMyimage.jpg" alt="thisImage" width="xxpx">
relative
<img src="images/thisIsMyimage.jpg" alt=" thisImage " width=" xxpx ">
Hope that helps.