For pictures, either way, you have to hit the blue reply button, rather than using the "quick" reply at the bottom of each page. But there are 2 methods.
1. You can attach images to the post. But they have to be really small or they won't take. Maximum file size 250k. You use the "attach file" at the bottom, browse for the pic, upload it, and if it's a small enough file the picture will appear at the bottom of your post.
2. Upload the photo to an online site like photobucket. These sites give each photo an address. Copy it. Then when you compose your message, there's a button for that. Looks like a little head at the top, just to the left of the "manager" button. Click it, and it asks you for a URL, paste the image address there. At the next prompt, type in L (for left aligned) and hit enter. At the next one, specify a size, I usually use 500 width. Hit ok, and it'll throw some gobblygook in your message. Don't mess with it, it's right, and when you hit submit that'll be your picture.