My guess is that the CD was inserted upside down and that is causing the trouble.
In any case the disk can be manually ejected by inserting a paper clip into the small hole on the drive.
The small hole is just below and to the right of the "eject" button.
You only have to insert the paper clip abour 1/4 to 3/8 of an inch to work. You will "feel" the resistance of the spring inside then the drive tray will pop open.
===this is from the Dell D510 manual======
If you cannot eject the CD, CD-RW, DVD, or DVD+RW drive tray
Ensure that the computer is shut down.
Straighten a paper clip and insert one end into the eject hole at the front of the drive; push firmly until the tray is partially ejected.
Gently pull out the tray until it stops.
You can check the manual that came with your computer for more information.
Hope this helps,
The Dell website