Well, we don't allow attachments, so you'll have to find some place to upload them. Does your ISP give you any space? Once you find a place to host them use the IMG tags to display them here, but you'll have to make sure the host allows hotlinking (many don't). 
Quite honestly it's a lot easier to make a web site and post a link
Sentra.net has a gallery you could use as well... but it's off line temporarily.
Quite honestly it's a lot easier to make a web site and post a link