How to understand the Sicilian Defense?

I don't like the Sicilian Defense because I don't really understand how to play these types of positions and score very badly with both white and black pieces.

I used to play the alapin variation with white but I scored horribly

I used to play the open Sicilian with black but lose all the time

Can anyone help me out? (Example: A step by step way to improve the Sicilian Defense)

Yeah, I went through basically the same thing you describe. I also tried 2.Nc3 closed sicilian stuff for a while.

I ended up liking 3.Bb5 lines (Moscow and Rossolimo) and 3.b3 against 2...e6

The fact that you claim you play the Open Sicilian with Black already says you don't understand it.  Black doesn't decide whether or not it's an Open Sicilian.  That is White.  If he plays 2.Nf3 and 3.d4, it's an Open Sicilian.  If he doesn't, it's not.

White:  Pick up and read this: https://www.amazon.com/Dismantling-Sicilian-Complete-Modern-Repertoire/dp/9056917528

Black:  Play a less complicated opening until you are well over 2000.  As a player that is over 2000 over the board, I can say that while I have played the Sicilian occasionally, just because it's popular at the GM level doesn't mean it's Black's only choice, and I myself am a lifelong French player.

Maybe you should be looking at one of the other three fully sound responses to 1.e4, whether that be 1...e5, the French, or the Caro-Kann.

Thanks for both responds!

@ThrillerFan

I am also a French defense player!

Can you recommend me a variation for white that is not very complicated (but sound) ?

I mean for white in the Sicilian Defense

"... Unlike in many repertoire books, de la Villa has consistently chosen critical main lines as his recommended repertoire choices for white. This means taking on sizable chunks of theory in already theory-laden lines such as the Dragon, Najdorf, and Scheveningen variations. ..." - FM Carsten Hansen (2010)

https://web.archive.org/web/20140627002658/http://www.chesscafe.com/text/hansen129.pdf

Some possibilities:

My First Chess Opening Repertoire for White
https://www.newinchess.com/media/wysiwyg/product_pdf/9033.pdf
https://chessbookreviews.wordpress.com/tag/vincent-moret/
Opening Repertoire 1 e4
https://www.newinchess.com/media/wysiwyg/product_pdf/7819.pdf

1 e4 A Comprehensive White Repertoire

https://www.chess.com/blog/logozar/1-e4-a-comprehensive-white-repertoire-blog-preview

https://www.chess.com/blog/Milliern/a-solution-to-all-of-your-1-e4-problems

A Simple Chess Opening Repertoire for White

http://www.gambitbooks.com/pdfs/A_Simple_Chess_Opening_Repertoire_for_White.pdf

https://chessbookreviews.wordpress.com/2018/04/01/opening-lines/

http://www.jeremysilman.com/shop/pc/A-Simple-Chess-Opening-Repertoire-for-White-76p3916.htm

Kaufman's New Repertoire for Black and White

https://www.chess.com/article/view/gm-larry-kaufmann-interview-gm-larry-kaufmann-interview-new-repertoire-for-black-and-white-book

https://www.newinchess.com/media/wysiwyg/product_pdf/9082a.pdf

A Chess Opening Repertoire for Blitz and Rapid by Evgeny and Vladimir Sveshnikov

https://www.newinchess.com/media/wysiwyg/product_pdf/9020.pdf

Playing 1.e4

https://www.qualitychess.co.uk/ebooks/Playing1e4FrenchDefenceSicilianSidelines-excerpt.pdf

https://www.qualitychess.co.uk/ebooks/Playing1e4SicilianMainLines-excerpt.pdf

Keep it Simple: 1.e4

https://www.newinchess.com/media/wysiwyg/product_pdf/9068.pdf

https://www.chess.com/blog/HanSchut/review-keep-it-simple-1-e4-by-im-christof-sielecki

1.e4

https://www.qualitychess.co.uk/ebooks/Negi_1e4_vs_the_Sicilian_One-excerpt.pdf

https://www.qualitychess.co.uk/ebooks/GrandmasterRepertoire1e4vsSicilianII-excerpt.pdf

https://www.qualitychess.co.uk/ebooks/1e4vsSicilianIII-excerpt.pdf

I can tell you what I play.  No idea if it suits you or not.  Much of what I do centers around Maroczy Bind positions:

1.e4 c5 2 Nf3 and now:

2...Nc6 - Open Sicilian

   Maroczy Bind vs Accel Dragon

   6.c4 against the Kalashnikov

   Main Line vs Sveshnikov (this takes some study)

   6.Bg5 against Classical (again, Study!)

2...d6 - Prins Variation - 3.d4 cxd4 4.Nxd4 Nf6 5.f3 - Frequent Maroczy Bind positions - Steamrolling The Sicilian will cover all of this

2...e6 - Kings Indian Attack - need to understand the difference between KIA vs Sicilian where Black goes ...d6 and KIA vs Ftench where Black goes ...d5.

Outside of the Sveshnikov and Classical, not a lot of theory.  Need to understand (NOT MEMORIZE) Maroczy Bind and KIA positions.

Here’s mine if you want to play an Open Sicilian against everything 

The old 6.Bg5 against the Najdorf

6.Bg5 against the Rauzer (Though Bg5 is more of a best move than a matter of taste)

Bxf6 and Nd5 before black Be7 against Sveshnikov 

Several Yugoslav lines against the Dragon (I like 12.Kb1)

6.N1c3 against Kalashnikov

6.Be3,7.Qd2 or 6.g3 against Taimanov

5.Bd3 against Kan

Nc3 and Bc4 against Accelerated Dragon with Dragon transpositions 

He has all the right information but will he be able to read and do all of that?

Knowing how to play 3 pawn structures will go a long way toward understanding the Sicilian: the Najdorf structure (Black pawns at d6 and e5), the Scheveningen structure (Black pawns at d6 and e6), and the Maroczy Bind. Forget about learning specific variations until you understand the strategic elements of these structures. The Dragon is a bit different, as it is strategically straightforward, though tactically complex.

Decent introductions to the 3 structures can be found in "Pawn Structure Chess" by Soltis and "Chess Structures" by Mauricio Flores Rios. Although there is some overlap between the books, each has independent value. For example, Flores doesn't cover the Scheveningen structure in detail, while Soltis does. But Flores has a chapter on the "descendant" of the Najdorf structure that results when Black captures an outpost on d5 and White retakes with the e pawn.