New to chess - can't understand two plays

Hello,

I started playing chess seriously a week ago (I knew the rule before) and I'm trying to look at some games with Scid in order to see which are the most common moves in some situations. I started with a Spanish opening (Morphy defense) but we are almost in mid game, that's why I posted it in this section (If it's not the right one, please tell me). So, here's the match:

After that the black can play 7) ... O-O or also 7) ... d6.

In the first case (O-O) the white responded c3 (30%), h3 (28%), a4 (22%), d4 (10%)

In the second case (d6) the white plays c3 more than 90% of the games.

So, I assume that this play is the best one (The percentages are based on 15.000 matches of people with elo 2000+ but I still can't understand it. Why c3 is good? You block your knight and also you can't move your bishop while if white played d3 he would have both moves available for the following turns. 

c3:

Prepares the d4 pawn push.

Gives the bishop an escape square on c2.

Guys your missing the boat with your advice, he "knew the rules before" and has been trying to learn more than that "for one week" and is now studying openings!  This is not an efficient use of your time at this point.  You need to learn beginner chess principles, such as rapidly developing your pieces, and get tactical practice so you don't give away free stuff and miss it when your opponent does.  Studying openings won't be particularly useful until you get strong enough that your games aren't routinely decided by who blunders more or worse.  There might be a few exceptions.  Trying to figure out why the Queen's Gambit is not just a free pawn, for example, is a sort of useful thing to do, but it can't be done looking at databases since only true beginners try to hold the gambit pawn.  But in general, no need to think about openings, just develop quick, and try to learn from your losses.  Maybe post some losses here for tips, if you don't have access to a human that can help.  There are some basic posts on learning strategies posted by Jeremy Silman on this website, if you can find them -- Silman has hundreds of articles here, most are too advanced, but there is beginner stuff as well.  

Art...you have been here long enough to know that this question...opening question, etc. is asked repeatedly, and the usual advice is ignored.  So now, i just answer the question.  If someone that learned to play a week ago wants to study openings, and retard their growth, that is up to them.

Thank you for your answers. Now it's all more clear to me.

I know that studying openings is not the best way to improve at the beginning but I already do some tactics (both exercises and theory) and I play games and try to revise them.

However, I personally can't be very efficient if I dedicate too many time to just one thing. So, I decided to study some openings for looking at how the principles are put into practice and for having a pool of similar matches (matches with the same opening) to understand how things can evolve differently.

Then I always try to understand why a certain move is correct (which is what I did with this thread). I'm generally really good at looking at particular cases, finding the general "rule" and then applying it in other cases and I'm just trying to exploit that.

That makes sense Gaemac.  Studying openings is definitely not totally useless if you approach it like you mentioned.  For example, as I mentioned, apply your approach to the Queen's Gambit.  Just don't worry about memorizing lines at this point.  Anyone that plays chess for a while will encounter many truly truly terrible players that have quite a bit memorized, and it is always quite humorous.  Moreover, when you do first start to memorize lines, you'll likely still be playing mostly players that have not done so, and you'll be out of your memorized lines very quickly.  Memorizing openings is just not a useful thing to do for quite a while.  

Fair point, IMBacon, its not a subject on which many beginners are willing to listen.  Gaemac is an exception in that he has given the subject actual thought.  

So, if I don't have to memorize the lines (and we all agree about that) and I can't look at the most common moves and trying to understand them because I won't be able to do so until I am "above 1800 ELO" what am I supposed to do?

What I did was:

Step 1: I saw a move and I didn't understand it. So I wonder if it was right or not. I looked at the database and I saw that it was the most played (by far) from the best players in the world. Does it mean that it is automatically the best move I can do in that situation? Maybe not, but until I am at least at 2500 ELO I can't argue with the best players, so I assume that it is the right move.

Step 2: "Why is it the best move"? Actually, just applying the opening principles, in the very short term 8) Nb3 (or also d3) is better because you develop a piece (or you free another one), but - as DeirdreSkye said - c3 is a small sacrifice for having a bigger advantage in the future.

Learning that was possible because I found a move to study and to understand. As it is impossible to study every possible move in chess, I just started focusing on the most common ones. I don't think it is a mistake.

And of course - as I already said in a previous post - this is something that won't replace tactics training: it's just something more.

I think the debate has gotten weirdly sidetracked.  There is clearly nothing wrong with looking at opening lines and asking why this move or why not that one.  As far as I'm concerned, the chief drawback is ts often rather hard to figure that out unless you have a human or a good book to consult -- engines and databases may help at times, but its an uncertain thing and answering the questions may simply be too hard at lower rates.  That is why I think this learning tactic isn't a great use of time for a true one week into it beginner, but if he wants to do it for variety, why not?