If you want the board to "host" the picture for you its quite simple:

1. Open up a post box like you normally would when you post a message.

2. Click on "File Manager" line (just below the box)

3. Browse your pc's files until you find where the picture that you want to post is.

4. Pick that picture and add that to the box; click on finish and just follow the normal posting steps after that.

BTW - You must add some typed message in the box and the photo has to be in a format that is recognized by the boards (i.e. "jpg").