The Sicilian - Closed Sicilian Basics
The Closed Sicilian Defense begins after 1. e4 c5 2. Nc3
Our best move is d6. From here white has a few options, the Grand Prix Attack, The Magnus Sicilian, The Traditional Variation and the Keres Variation. If they play f4, the Grand Prix attack, play a6, kind of a Najdorf-esque move. Oh, by the way, before you read this you should learn the Open Sicilian here.
After they develop with Nf3, respond with Nf6. If they play Bc4, we play b5, bishop can't go to b3, because we trap it with c4. If the bishop goes to d5 trade it for the knight. If they recapture with the pawn, play Nd7, if they recapture with the knight, play e6 followed by Bb7.
If instead of Bc4 immediately they play a4 to try preventing the b5 push, we will play e6, because we prepare the d5 push. If they play Bc4, d5, trades and natural development. If instead of Bc4 there, we play Nc6.
If they go for the Magnus Sicilian with d5, we take and when the queen takes we play Nc6. The queen will go to d2, and the point of the Magnus Sicilian is to castle queenside, with b3 and Bb2. We will play e6, Nf3 and d5. We too likely castle queenside.
If they play the Traditional Variation with Nf3, this will likely transpose into the Open Sicilian, which is why I suggested you learnt the Open Sicilian before this. If they don't go for the Open Sicilian, we will fianchetto the dark-squared bishop and dominate the dark-squares.
If they go for the Keres, this too turns into the Classical Sicilian. They play Nge2, we play Nc6.
This is why I emphasized that you learn the Open Sicilian.
Other Variations
The McDonnell Attack is one thing you might encounter while playing the Sicilian Defense. After we play c5 they play f4.
We will play d5, and when they take we play Nf6, the Tal Gambit. If they play Nc3, take the pawn. You have an active queen and if they kick it with c4, move it to e4 with check. If they played otherwise with Bc4, take the pawn, and if they trade, thinking they can kick the queen with Nc3, you can take on g2.
If they defend with c4, play e6 and gambit the pawn to develop the bishop.
If they decline the d5 pawn with e5, we will play Nc6 and develop our g8 to either e7 or h6(more likely h6).
That's all for the Closed Sicilian, way more simple than the Open Sicilian! Good luck and have fun with this, goodbye.
