I need advices from all of you, thank you...

Learning d4, is a second task for most players. Learn e4 positions first. This gives you a basic understanding of positional equality, and not making mistakes within the first 8 moves. 

Don't try and sac pieces too much, opponents can easily re balance things if the sac isn't perfect. 

You're right, najdorf is much more fun that dragon. 

The scotch is very powerful, a very good weapon to have in your holster. I suggest looking into the Italian. 1.e4 e5. 2. Nf3. Nc6. 3. Bc4. This is a very tactical, and very powerful opening. You may even try the Ruy lopez. Which is merely 3. Bb5. Very good game, fun too. Just study the basic openings of e4 positions first. This will help very much. 

PS. Your grammar is decent, alot better than some kids that originally speak English.

You are brave in chess, where my weakness is that I am valiant and too cavalier at times.  My friends say "whatever", because they don't play chess. I seldom drink beer, but when I do, I prefer Dos Equis.  I am the least interesting chess player in the world.

Your english is pretty good so don't worry about it :-)