Use an information task to show your participant arbitrary marked up content, such as an instruction.
Main text formatting instructions
This task has only one parameter: the main text field. It can be filled with whichever text you'd like to present to the participant. Besides regular text, you can also add formatting and images. When you press the insert Image button, a dialog will appear; in the source field, you'd copy the URL of an image. If your image is not yet on the internet, one way to host it online, is to include it in a public Github repository (make sure to link to the "raw" file) or use an image hosting service such as imgur.