help for beginner to understand chess

Hello everybody. I would describe myself as a new player since I completely understand chess rules and I played chess since I was kid but I've never think about some tactics or openings or anything. So, i read some articles and forums and I came across this problem: I understand that basically every opening has some advantages and disadvantages but is it necessary to learn all openings so you can respond on oponents opening? Or are there some generally strong openings which can be played against every opening? It might sound like stupid question, but I'm really new to the "pro" chess, so if you have some advices or you can recommend me some literature or articles I would really appreciate it. 

And second problem. I really dont understand what happens after the opening. I mean, I tried to play some opening, but when I make those few moves which are given by opening, I kinda dont know what should be my next move.  What kind of articles should I look on to understand this aspect of the game? Or can somebody explain to me what should I aim for to understand this problem. 

Thank you very much in advance. 

Beginners don't need to know openings, just opening principles. Put pawns in the center, develop pieces into the center, and castle.

I made a post here titled "Step-by-step improvement" that has a lot of general information about getting better for beginning and intermediate players. The advice still holds true for advanced and expert players as well; search the forum for it here and I hope it helps you, good luck