Lenovo flex 2 15 inches optical drive?

I have Lenovo flex 2 15 inches, and it has an optical drive, but I can't find the button. How can I open it because I want to burn a CD. I looked all over it, there's no such a button for it

Gre

Go to Computer > Right click CD/DVD drive > Eject

Go to my computer, right click on the optical drive icon and select 'eject' or you can just start the burn process, it will open up the drive automatically for you to put a blank CD in it.