After you click on the "New thread" or "Post reply" button, you'll get the screen to start typing your post. If you look right above the space where you type in your post, you'll see some button there marke "http://", "@", "img", and others. If you want to post a link, click on the http://, and a window will appear. Paste the link in that and you are all set. The same with a picture...click on IMG and paste the link for the pic and its GAME ON!!
There is a testing area on this site, toward the bottom. Go play and experiment to your hearts desire!!!