I would just like to clarify first of all that I don't have a disc, and I didn't download it - it came with my computer when I bought it.
I've got the serial code and everything, but I can't find a way to download the Photoshop Elements trial so I can put in the serial code (none of the ones I could find work).
Download a trial version from
Ensure that you follow the Very Important Instructions on that page before you click the download link otherwise the link will not work.
Launch the trial and enter your serial number to license it.