Screenshots are the primary way of describing the issue.
While it’s true that you can’t upload picture in a direct way, you can embed pictures into your comments via HTML.
How to embed pictures...
Upload your picture to an image hosting site e.g. postimage.org (my favorite).
Copy the direct link of your picture. A direct link usually ends with your picture file’s extension e.g. .png, .jpg etc.
Use the HTML tag
<img src="YourDirectLink"/>(keep the double quotation marks).
<img>tag into your comment.
I hope this helps.