The Ruy lopez. It is simple and I don't use it much but it will give you an understanding of positional play and the importance of gaining a tiny advantage at the opening of the game. Good luck and stay in touch, I'd like to play again sometime!
The beginnings

When starting off, it is perhaps better to learn the principles of the opening rather than openings themselves. These include, but are not limited to:
1. Developing your pieces towards your opponent.
2. Establishing a pawn centre.
3. Getting your king to safety (almost always by castling)

The Ruy lopez. It is simple and I don't use it much but it will give you an understanding of positional play and the importance of gaining a tiny advantage at the opening of the game. Good luck and stay in touch, I'd like to play again sometime!
If you consider the Ruy lopez simple then I'd love to know what openings you think are complicated!

Atomichicken is right, the Ruy Lopez is possibly the most complicated opening for 1. e4 e5, by which I mean the one that has had the most analysis and the most lines developed. It can be considered the 'main line' of 1. e4 e5.

Nytik is 100% right. Lines themselves are not useful if you do not have basic understanding of the opening principles. To add to what Nytik said, here are a few more:
1. Knights before bishops.
2. Try and control the center.
3. Centralise your pieces.
4. Get a lead in development if you can.
5. Place your pieces actively (where they control most squares)
I hope that that helps.
OG

be sure to study openings, generally, 0 hours a day.
This is in contrast to tactics which you should be studying ALL THE TIME.

Which are the first steps a begginer must study of Chess Openings?
- Replay games of your favorite masters, and try to emulate them. Starting with Morphy is a good choice (World Champions learned from each other and played more and more sophisticated chess; so start with the oldest. Morphy was considered the best in the world in his time). Any other favorite player will work as well.
- After a game, look up the opening in some book, database or games collection, see where the game first took an original road, and compare. Was the new move a mistake, what's normal, why is that probably the normal way, etc.

Starting with Morphy is the best thing to do, definitely. He started the ideas that we use today. One has to understand one's past to be able to understand one's present and future; very true in this case. Before him was junk though; we all probably play better than those people.
But modern chess players' games are good to study as well.
OG
Which are the first steps a begginer must study of Chess Openings?