To post pictures you need to get the link to the picture itself, not the page it shows on. Right-click on the picture as it's displayed on flickr, and select "Copy Image Location"
It should look something like this, without the spaces:
http : // farm4.staticflickr.com / 3849 / 14678311575_e8bf9486a1_z . jpg
That's what you post in the image dialog when you're creating your posting.
Nice camper, and excellent tiedown system. The under-truck brackets are designed to withstand road hazards to a certain degree. Of course if you're slogging through mud or rock-bouncing with the truck, you might want to take them off.