Website - Softwear Problems

The creation of my pages within the website have mostly been completed at home using CS5. When taking my work into school for feedback i found that the school could only run CS3. To solve this problem I firstly opened my work in CS5 and saved the website in a CS$ format and then downloaded CS4 and then saved the project as a CS3 format.

When I took this copy into school everything opened in the program but when selecting F12 to view the website certain parts of the page will not load at school. After seeking advice from my teachers, the problems which me and Melissa where having with viewing the website at school are now solved. They where solved by saving the website in a CS3 format and saving the JPGs which would not appear a GIF images