How should I play wiith White and Black in the Sicilian Dragon? How should I play with White and Black in the Sicilian Dragon? 

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1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 g6 6. Be3 Bg7
My personal opinion:
If you are really annoyed of your opponents opening preparation of early dragon then just avoid it in the beginning. There is a friend of mine who crammed the dragon at length. I was extremely annoyed. To avoid the dragon I started to play Morra's Gambit. Morra's Gambit is quite effective. It can take your opponent out of the opening. You can try Morra Gambit if you are an attacking player otherwise do not go for it. You need to play quite sharp in Morra's Gambit. If you lose your tempo then the Gambit will go in vain and the opponent will get a clear advantage of 1 pawn.   

Short answer:

If you want to deal with the position after 6...Bg7 then you will have to learn the theory. The main options are  7.Bc4,Be2,f4,f3.  Other option are 7.Bb5+, even moves like 7.a3,a4  or  7.h3,h4 are playable. 7.h4 is quite attacking and 8.h5 can be sacrificed for a open file. 7.g3 is also playable but it seems like a dull move because Bg2 won't be very effective because black's Night can soon jump at g4. 

In 7.Be2 or Bc4 line sometimes after some moves there is an option of retreating the bishop on f1.   

There is so much theory that a full fledged book can be written.   

In some lines you may go for opposite castling but you will loose your small opening advantage. It will be still playable because the game will become highly tactical and attacking for both the sides. If you are good in tactics you can try this.   

If you do not like very much Black's dark bishop on g7 then you can double your bishop with Queen(7.Qd2) and force Black to trade the bishops. Again doing this will give up your opening advantage.  

If you are not playing at GM level then small opening advantage doesn't matter. Infact the whole opening doesn't matter.   

The real answer to your question is read a book of dragon variation and use latest stockfish engine to analyse different lines :-)