Here are instructions on putting images in your forum posts:
First the image must be available online, I'd like to add the ability to upload images directly sometime in the future, but until I get that figured out the only way to post an image is if it is already online.
If the image is only on your hard drive you can upload it to an image hosting site. I recommend Flickr If you already have a Yahoo ID you can register with that, otherwise you have to sign up for a Yahoo e-mail account.
After you've uploaded your images click on the image you'd like to post and its page will come up. Look above the picture for a little magnifying glass-shaped icon labeled "all sizes," click on it. Now select a size appropriate for the forums, less than 500 pixels wide will be best. after you choose the size look to the bottom of the page for the code you need to insert.
highlight this text and copy it.

then paste it into your post.