You can use the "paperclip" in the "reply" area, and that's quick and easy. Or, you could post them in your gallery and then post them here by copying the link. Those are the easiest ways.
You could also just post the link here if it's hosted at someplace like photobucket. I like the first way- the attachment way. It's easy and you can just put a picture in the post that's on your computer without hosting it any place else first.