click browse and then pick the picture from your documents that you want to upload, then it will give the a http link
and in the post you want the picture put the link inbetween [img] and [/img]
heres some other upload sites
www.imageshack.us www.photobucket.com
if you didnt understand how i explained it then next to your log out button it says faq, your question can also probably be answered in there