If your pics are on the internet, you need to open the pic in your browser so that the address ends in a file extension such as ".jpg". If that's the case, then you just click on the picture icon in the menu bar at the top of the box that you're writing your post in (it's to the right of the smiley face and it looks like a very small, black-and-white picture of a mountain with a sun rising above it). You then simply copy and paste the web address of the picture (the one that ends in ".jpg") into the box that pops up when you click on the little picture icon.