Go to the bottom of the mobile version of the site and click 'classic view' or whatever its called.
in the reply box of classic view, there are a bunch of icons above the text area. The 4th in from the right is a square. Click it- that's how pictures are loaded. You can then link them from a site like flickr or just upload them from your phone. uploading from your phone is easiest.
there are 2 tabs to choose from, make sure you choose to insert from computer. choose 'select files' and you will have access to your phones pictures. select the one you want and then confirm you want to upload it.