When you make a thread, if you scroll down, there's a button that says 'Manage Attachments'. Hit that and it'll bring up another screen. If your pictures are saved to your computer you can hit browse and find the picture in your files and hit upload. If you have the URL of the picture, you can paste it in the second option that says download from URL and hit upload. After you hit upload it will automatically put the picture on and after your done, just close out of the 'Manage Attachments' window and hit submit reply on the regular thread and it'll show the picture(s).