As has effectively been indicated, you can't directly put a picture onto AB. You need to put it onto a photo-hosting site and post a link to it here.
Tinypic is by far the most popular site for doing so, as you're not required to sign up for an account. You can simply upload your picture straight away. If you need detailed instructions you can find them in my post here:
http://www.theanswerbank.co.uk/Technology/Question1425764.html
Example of how your picture will appear:
http://tinypic.com/view.php?pic=11lmzxz&s=8#.VY2FjUbXsx0
(Yes, they're mine!)
However Tinypic only lets you upload a single picture at a time. If you want to let us see an entire gallery of your pictures you need to use an image-hosting site that offers that facility. I use Rajce. The instructions are all in Czech but you can overcome that very easily if you go via Google Translation:
http://translate.google.co.uk/translate?hl=en&sl=cs&u=http://www.rajce.idnes.cz/&prev=search
Sample galleries:
http://ukcatlover.rajce.idnes.cz/
(Yes, they're mine again. No, I'm not a Morris Dancer!)
However you can use other (English language) websites, such as Webshots or Flickr just as easily.