At least you know your music -- Led Zeppelin rules!
Dazed & Confused

Hi there. I'm in the same position as yourself. I'm trying to get seriously into the game and have studied several openings, yet the second an opponent makes a move thats not in the plan ( so to speak) I panic!! help!!!!
Pick an opening move. Let's say 1.e4. Play it every game, so you're on familiar territory.
Then, pick "openings" to study against 1...e5 and 1...c5. The open game and the Sicilian. These will be the most common responses, so your time won't be wasted.
Now, ignore those for the moment, and accept a couple general opening principles:
You want your central pawns to advance. So e4 and d4 are your first priority.
You want your knights to develop...probably to c3 and f3. Often, you have to wait until you develop one of your knights until you can get in d4. That's okay.
You want to develop your kingside bishop somewhere it's doing something useful...or at least somewhere you won't lose it.
You want to castle, quickly.
You want to complete your development by developing your other bishop and your queen, so you can connect your rooks.
Do all this as quickly as possible, with the caveat: be willing to make other moves if your opponent threatens something, or leaves something vulnerable for you to attack.
So then, back to your repertoire...
Follow your chosen ...e5 or ...c5 repertoire as far as possible. When your opponent goes out of book, revert to opening principles. So you play 1.e4c5 2.Nf3 and your opponent plays ...a6?! What do you do? d4. Then develop as per principle.
You play 1.e4e5 2.Nf3 and your opponent plays Qf6?! In a perfect world, you'd know that theory says 3.Nc3. But what if you don't know that? Can you just play according to the same old theory, and push an immediate d4? Yes! And you'll be fine doing it.
This way, if your opponent plays 1...e6, you know what to do. Complete your first priority! d4! Congratulations, you're playing the French. He'll probably play d5, and then voila...opening principles again. Is my opponent threatening something? Yes! dxe4. So do something about it. Protect it by developing a knight. Or capture him before he captures you. Either way just makes sense, and not coincidentally, either way is 100% grandmaster sound. Then, just continue to play by principle.
If your opponent plays 1...c6, you know what to do.
If your opponent plays 1...g6, you know what to do.
If your opponent plays 1...d5, you know what to do.
If your opponent plays 1...h6, you know what to do.
1.e4 h5 2.d4 h4 3.Nf3 h3???!!!!! DON'T PANIC! After 4.Nc3 hxg2 5.Bxg2, you have a nice advantage, just from following principle in the face of a berzerk opponent.
It's all just basic principles. Don't over think it all. If you want to know "grandmaster openings", just worry about one or two at a time, and when they break down, fall back on what you know.

I have started to seriously study chess about two years ago and I had the same problem that you guys have: what to do in the opening, when there are no clear targets and/or threats to focus on? Luckily, I came across of a great book by IM Josh Waitzkin called "The Art of Learning" in which, among many other things, he says that in order to get better in any competitive sport, you have to be prepared to lose a lot in the beginning to build a solid foundation for your game and not focus on how quickly you will start to win. Because of this, I have never been a fan of "learn two openings and two defenses and stick with them" approach. Puting aside for the moment the fact that your meaner opponents might refuse to play the openings that you have so diligently studied and the fact that you will, as Craigrob observed, have a panic attack every time when you reach the end of the opening ends and the middle game begins (because you will be leaving, to use Waitzkin's words, your "comfort zone"), there is a much bigger problem with this approach and that is:
YOU ARE SUPPOSED TO BE ENJOYING CHESS AND INSTEAD YOU TURNING IT INTO A STRESSFUL EXAM!!
So, instead of memorizing moves, treat the game as an uncharted territory that you have decided to explore. Have fun exploring and don't worry about winning and losing at first (I don't mean that you shouldn't play carefully, I mean that you shouldn't be emotionaly dependent on the results of your games like "Oh no, I lost, I'm worthless!"). Most world champions started their chess career as kids who had no idea what they're doing (except Capablanca who started it by correcting his father's illegal move) and at least one World Champion (Kramnik) has missed a mate in one while he was a champion, so you losing a game (or hundred) is not something worth being uppset about.
Instead of trying to play by the book, try learning the basic principles and goals in the opening:
1. Activating your pieces (moving them to good squares) as quickly as possible.
2. Castling to get your king to safety.
3. Taking control of the center of the board.
4. Connecting your rooks.
5. ... while preventing your opponent from doing those things.
Be imaginative and don't be afraid to try out new ideas because either you will find out that it's good or you will figure out why is it bad. You will also come up with the tast for some elements of a position (for me as white it is a Bishop on c4, I would like to build him a house there) and a distaste for other elements. When this happens THEN you have criteria on which you can start choosing which openings and variations you want to study.
After doing some reading here on the forums, I read that one should learn 1 or 2 openings and stick to the main line. Well, some opening moves only have 2-3 moves per side before they are done, what then?
I tried to watch a few Masters games, but since I am totally clueless as what the Masters are doing, they think in 3 dimensions while I can't even think past one
, that does not help either.
I tried to play an online game and guess what? My opponent did NOTHING close to what the opening I was doing. What do I do in that situation?
I started to go through the Chess Mentor. Should I just stick to that for now?
Thank you for your time and effort.