As the guys have stated you can not attach photos or images to Perb.
What you see is a hotlink to a site that holds the picture.
To reply to a post and add a pic use the "Post a Reply" link at the top or bottom of the page. Do not use the "Fast Reply" box.
Say what you want to say and then add you link to the pic by first clicking the "IMG button" in the VB Code section. A popup box will ask for the link. Add the address of the picture or image you want to attach. Hit enter then "Submit Reply" button. Your image should now be shown on your reply (if you did it correctly).
To find an address of the image:
Go to the webpage with the image and right-click on it. Select properties and it will show you the URL of the image...copy and paste it into the popup box.
If you have an image on your hard drive, you must copy it to a website like the guys said.
Thats how they do it.