Error 403

Hello, I am trying to finish a project for my school assignment and I keep getting the 403 error message stating that I used unauterized content. However, every picture that I used was allowed under the free account. I still can't publish my webpage and this is worth 10% of my grade. I have been dealing with this since for about 3 days and my deadline was yesterday. Please assist me on what I should do. Thank you.