If I'm not mistaken, you have to have space on a server or use a third party server like
http://www.boomspeed.com/host/ . (It used to be free but now I think it costs to post there) There are feree ones out there but I don't remember where I used the last time I posted a picture. But basically you download the picture to the server and then you post the url (address) to the picture on that server in your post on the board you want to post it on. I think if you post it with html language (enclosed the link in between
), the picture shows up in your post, or you just post the link and people can click on it to see the picture.
As I said, it has been about 3 years since I posted a picture on any board but if I remember right, that is the procedure I followed.
Hope this helps you. You just need to look for a server that still offers free space. (I'm sure there are some).