Snippy,
It is fairly easy, just read the FAQ section next to Who's Online.
For images, you use photobucket.com and then use the image tag pointing to my images. For ex. [img]http://pathtofile[/img] Make sure you don't post to big of pictures, the FAQ section tells you what guidlines to follow.
For addresses, use [url]http://address[url] and the link will show up as the actual address in your post. Or you can get fancy and do [url=http....]This is the link to my website[/url] In this example the users will see your phrase as a link, not the address.