I tried to use a picture  /img/Paul.png.

And the picture is not loaded.
error 404.

I tried to go 1 folder before but still does not work.

                <button class="profile-icon dropdown-toggle" type="button" id="dropdownMenuButton" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                    <img src="/img/Paul.png" alt="Profile Dropdown" class="dropdown-img">
                </button>

this is how I defined my code in html.