You need to have your pics hosted somewhere first. When composing your post, click on the button that says IMG on it. The paste the address of the photo after it, then click on the IMG button again. When you are done, it should look something like this:
"I think it might be helpful for everyone to remember that the purpose of a forum like this is to EXCHANGE IDEAS, not dictate what is right or wrong or good or bad. If you disagree with what someone else is suggesting, you can say so without being argumentative or completely slamming the guy (or girl)." - Smynx
Some places, like geocities, don't allow remote links to images, so if you follow that formula, it still might not work, depending on where you host. As a member of this site, you can open up an album here to hold your pics and they'll always work for you.