Not sure if this has been answered, but it appears that you are skipping a step which is entirely external to your computer and to this website; i.e., a photo-sharing service on the good ol' Internet.
You must upload your pics to an image-hosting site and link to them from there.
If you'll notice (right click on any image you've seen someone post) the images you're seeing in the comments are actually being linked to in the comment itself.
Photobucket, flickr, etc. are just a couple of these services.
Here's an example of a screen snip I did and uploaded to a photobucket account:
Let me know if this makes sense, you have further questions, neither, or both...:smile:
You do not have to use an image hositng site. I save them to my computer and upload from there. Works for PDF's, too.