Here are some instructions on linking to images in a message on TriumphRat.net
Step 1 - The first step in posting a picture is to have your pictures posted somewhere on the internet. There are many free places to host pictures. Here are two places where you can signup and post pictures, FREE.
Photobucket
Flickr
Step 2 - Post pictures by following the instructions on the respective website.
Step 3 - Find out the URL. Once you have posted pictures on either one of these places you need to find out the URL to the picture themselves. On Flickr you can either just right-click on the image and find the URL by looking at the properties, or click on 'copy image location', or you can click on 'See different sizes', on this page it has instructions for posting to the internet, and it has a box with the URL. Copy one of the URL's, like this "http://static.flickr.com/78/158231249_4a5b2e3b2f.jpg?v=0".
Step 4 - Come back here to TriumphRat.net
Step 5 - Click on the

button.
Step 6 - Paste the URL into the dialog box, like this -

Step 7 - Make sure after you add an image you hit enter, otherwise if you add more pictures they are to the right, not below.
If you decide to link to an image on someone else's website and do not have permission you may be asking for trouble. Some websites only allow images to be grabbed from their server if the requesting page is on the same server as the image. If someone else is trying to grab the image, the server replaces it with a placeholder image. Most placeholder images are not friendly. So, in other words, use a website like Flickr or Photobucket.
Hopefully this has been helpful, if not, just e-mail me and I will try and provide more detailed instructions.