Hi Tony,
to the site.
If you are posting a new thread then about halfway down the page you will find a button labelled "Manage Attachments". Click on there and then you can browse and upload up to 8 images for the post. The preference is for jpeg as the site will then generate a thumbnail for the image in your post. This won't happen with bmps. Also you will need to keep your image size below 150kb.
If you are replying to a post, rather than typing in the quickpost box go to the "Go Advanced" page. This will bring up the same page as the new thread page.