Not sure how he did it

After Ng4 then after h3 Nxe3. He basically chased your knight till h8 and then mobilised his pieces to attack you. You are ranked 1276 while he is 1478 but you should not be that scared of your opponents. Try and eat some weetabix or something.

I agree with CCNoob. Also, early in the game, you were castled and he wasn't - I would have pushed my central pawns to break open the center. Also, later you voluntarily started moving your pawns protecting your king, which looked very self-destructive to me.

When White plays these closed sicilian lines (i.e. he doesn't play an early d4) he is generally going to try to attack on the kingside with his f, g and h-pawns (even though he may well castle kingside himself). Black can often counter this with active play on the queenside and perhaps by playing his own f-pawn to f5.

Here is another game where you are playing someone 1400+. You need to work on your tactics.

Thanks all. So a central push earlier might have worked. OK.

would 24 ....Bh4 helped?

No, White's 24th move threatened 25. Nb6 and 24. ... Bh4 doesn't stop that. After 24. ... Bh4 25. Nb6 Q moves 26. Nxd7 Qxd7 27. Bxf6+ and Black loses his queen.