Take a picture and post it on the forum for us. Everyone in this forum has received a Macbook Pro without this additional piece of covering, so it's normal for us to assume you're simply overlooking the obvious. Don't retaliate, provide us more to go off of.
Still until we can actually see what you are talking about, it is just guesswork which side of the notebook you are looking at, or if what you are looking at is one thing or another. Without an image, we can't tell if it is the thin foam that often comes with the machine, or if somehow the optical drive foam is on the loose, or if you are talking about the thin plastic strip that molds the edges of the machine which is bothering you. Give us an image, and we can tell what you are looking at. Just describing it by text is not going to be sufficient.
"...Chapter 2, pg. 20 does not describe the situation. It's a picture of the MacBook Pro showing what could be a latch, but there is no label, as you will see when you look at the page again."
As you might have suspected your advice while good for the original poster seems to have been misdirected. When you want to reply to the original poster, find an individual post of the original poster, and click on reply to that post, so it is obvious your reply is intended for them, and not for someone else. I know this forum can be confusing to the uninitiated, but with time I'm sure you'll get used to it. Just so you know, others have indicated what you have already. I don't know how you are viewing the forum, but it is most obvious in My Settings -> Topic Page View -> Threaded who has replied to whom, except if you are using dialup or behind a large firewall on a long thread, in which case Tree view loads quicker.
I'd recommend turning the computer around 180 degrees. The "strip" you're talking about is a back panel, and should be left in place.
At the opposite, front end, you'll find the latch that's shown in the illustration.
Press this in - at the same time insert a nail or finger between the lid and the bottom portion of your MacBook Pro. Raise the lid, while depressing the latch.
You will now have succeeded in opening your MBP.
To close - just snap the lid shut. To open, repeat the above steps.