It's not painfully obvious, so here is a quick tutorial on how to add images that live on your computer to your posts:
1. When replying to a thread, click the 'Go Advanced' button next to the 'Post Quick Reply' button at the bottom of the page.
2. Click the little paper clip icon - this is the icon that indicates attachments.
3. You should see a little pop up box titled 'Manage Attachments'.
4. Click the 'Browse' button next to any of the ten fields.
5. Browse to and select the image file y