you cant insert them directly or the server would eventually run out of room. you just need to get the address and put it in-between the image tags. the picture must reside somewhere else on the internet like fileden or something like that. IE: [.img]domain.com/picture/example.jpg [./img]-- remove the periods, i only put them there to make the whole thing show up.
I'm sure someone will correct me if i did that wrong