It can be a bit complex compared to other sites, but is fairly easy once you do it a time or two.

You'll need to post your photos to a photo site where each is assigned a URL. I use photobucket.com which is free and pretty simple. Many other sites are out there. From there you will need to click on the "image" block in the menu below the text box and insert your pasted URL into the pop-up display. If this doesn't work, goto the Admin section and ask and a more tech-savvy forum member can help you trouble shoot whatever issues you may be having.