You really didn't ruin the disk. It is a re-writable one that can be erased and used over and over.
I don't know your computer, but somewhere there is a place the says, "eject disk". Click on that and it should pop out. Sometimes, if you re-boot your computer and push the button on the drive, it will open for you. Go online and ask, how to eject a disk that is stuck in the cd drive. It will give you instructions. It's ok. You didn't do anything bad. Whenever I mess something up, I just go online and ask a question about it and most always find an answer and a solution.