let me make it easy for you
click this link:
http://www.dropbox.com/referrals/NTIzNjEzMzA5
install dropbox (probably best thing you will install on your computer)
it will make a folder on your computer in your documents call "my dropbox"
open that folder, should see one that says public
put your picture in there
right click on it, click on "copy publick link"
come to can reef, click on the image tag when creating a post, and paste the link you just copied in.
works great, you will start seeing this more and more around the web as it catches on, probably one of the hotest things right now.