To attach photos click on Go Advanced
scroll down to Attach files / manage attachments- click
Where it says upload photo from your computer click on first ( choose file((you can add up to 5 photos)) - one at a time )
when you choose a photo it will come up in a box- at the bottom of the box it says actual size- click there ( I always choose * medium* which has always worked for me. ) then at the top click Use
after you have added the ones you want click upload- off to the right
once they have uploaded you can X out of that screen and go back to your post- click submit