First take a look in Device Manager and expand "CD/DVD Drives" to see if a CD drive model is listed.
If one isn't listed then your laptop doesn't have one.
What you can see on the right-hand edge of your laptop is most likely a plastic blanking plate covering the empty bay where a CD drive would normally be on those Asus models which ship with one fitted. That's why there's no eject button, it's just a blanking plate to cover the empty bay that's behind it. An optical drive was probably an optional extra on your model.