Start a new thread under Member Profiles or For Sale topic.
Put in the text you want next to the photo and press post.
Now you should see the first message at the top of the screen in a box with a clickable link.
Click it, click browse to locate picture on your computer (jpg, less than 18K) then click load.
Click close window.
I would suggest For Sale for free stuff - just put FREE! in the title to get peoples attention.