Hi Axel,
Thank you for your questions.. Basically what you need to do is create an HTML IMG TAG. If you google HTML IMG Tag you will see the formatting, not sure I can paste it here as it will appear as an image
Basically you have an HTML tag that starts with < IMG and then you add in src="[YourField] and then end it with / >.
You might review this site:
http://www.w3schools.com/tags/tag_img.asp
You don't need to specify the width or height there.
Thanks,
Chad