Besides the keyboard command
you can use a program called Tinker Tool, to add the Eject button to your top menu bar.
http://www.bresink.de/osx/TinkerTool.html
Install it, and run the program.
In the application click on the "Applications" button on the top, then click "Add eject button to Menu bar", then click the "Update Menu Bar" button.
When you are done, you will have something like the image attached.