How is this a winning position for white?

Question

[FEN "r4r1k/pbq2p1p/1p1ppPp1/8/2P3P1/PP6/R2Q2P1/1B3R1K w KQkq - 0 1"]

1. Qh6 Rg8 2. Rf4 e5 3. Rf3 Bxf3 4. gxf3

This is what I got from "ChessCademy -> Attack and Defence -> Attacking Castled King -> Combining Focal points" lesson. After this small play, I got :

Excellent! After attacking the g7 square, black is forced to close off g8 as an escape square for his king. From there, you opened up the h-file, resulting in a decisive attack.

I don't understand how White got an advantage and there why Black did the moves he did. Sadly, I didn't find a way to get the more in depth analysis on the website, or have variations of games that I could play. It would be wonderful if someone could explain to me, or show, why White is winning and was this the best course of action? Is there anything else Black could have done to better himself?

Answer 1

Qh6 threatens Qg7 mate, so Rg8 was the only way to defend.

Now if white finds a way for a rook to get to the h-line, Qxh7 Kxh7 Rh+ would be mate.

One idea would be 2.Rf3 Bxf3 3.gxf3 and then execute this idea with 4.Qxh7 and Ra2-h2. Unfortunately in this line 3…d5 attacks the h2 square and 4.Qxh7 Kxh7 5.Rh2 is foiled by 5…Qxh2.

So white plays 2.Rf4 first, this threatens g5 and then the execution. Therefore black forces the rook away with 2…e5. But now the Rf3-idea works because d5 no longer allows the queen to attack h2. No more way to prevent Qh7 and mate.

[FEN "r4r1k/pbq2p1p/1p1ppPp1/8/2P3P1/PP6/R2Q2P1/1B3R1K w KQkq - 0 1"]

1. Qh6 Rg8 2. Rf4 e5 3. Rf3 Bxf3 4. gxf3 d5 5.Qxh7 Kxh7 6.Rh2