How to position images?

I'm trying to position an image at a particular position on the sheet. I can get the image on the sheet, but it won't listen to the CSS position or size settings. What am I doing wrong here?

html:

<img src="https://i.imgur.com/ewnhbrA.png" class="agility6">

CSS:

.agility6 {
  position: absolute; 
  top: 200px;
  left: 20px; 
  width: 100px; 
  height: auto; 
  border: none; 
}

I often find that the parent element is the root cause of positioning problems, either because of it's display type and/or is missing positioning itself.