You've posted in the Forum Comments forum which is for issues with these forums themselves. I'll get a moderator to move your post to a product support forum. That being said, they're gonna have to make a 50/50 guess since you haven't mentioned if you're using Photoshop Elements or Premiere Elements.
Keep in mind, this is a public forum, so please don't post your serial number to anyone.
Just got my elements 15 disc which my PC (Windows) does not recognise. I understand that I must register and insert my unique serial number that was on the box but dont know where to go to register the product. Can anyone help?
The serial number should be IN the box, not ON it.
If you optical disc drive is not reading the disk, download and install the "trial" version. It is exactly the same. When you launch the program there will be a dialog asking you if you want to use it as a trial or enter the serial number.
You can download from here: https://helpx.adobe.com/premiere-elements/kb/premiere-elements-downloads.html