You have about 3 options
1. if the photos are already in your own website or on the net somewhere, all you have to do is hit the IMG button when you make a post, then copy and paste the URL of the picture (an only the picture, right click, properties, URL). It will automatically place the code for the picture to show up in your post.
2. If its not on the web, you can join one of the free pic hosting sites, and then do the above. Most of them suck,and really limit the availability of your pictures.
3. Shell out $20 or $30 to become a premium or gold member, and you can upload your pictures right onto BFC. Membership lasts for a year, and comes with a few other nice features.