I know how to embed a video from YouTube in the Comment section but how do I do that with a image and/or gif?
Firstly, look for threads that may answer your question before posting. There is one called the KYM Guide to HTML/Textile in site related section.
That brings me to our second point; questions go in Site Related, not general. I’ll move the thread.
To answer your question, simply put the URL of the image (view just the image, then get the URL of that page) between two ! marks with no spaces.