By move 29, make no mistake about it, black is dead lost. There's no way to overcome a 3 pawn disadvantage in a king and pawn ending unless you can force a promotion very quickly. In the case of your game, there is not even a way to get a passed pawn.
4. ... e5. Yes, this is not standard Sicilian. The reason is that you leave a big weakness on d5 and you leave the diagonal to f7 weak since now can't play e6. I would recommend against this line as it gives white easy ideas.
6. ... Nd4, hopefully this is the last time you set yourself up for Legall's mate. ;-)
7. ... dxe5. I don't think you have anything better here. Your bishop is attacked and you certainly can't play 7. ... Bxd1 8. Bxf7 Ke7 Nd5#
Take a look at move 16. You have no developed pieces and there is a lot of space around your king. This favors white significantly.
Your opponent sacrificed a piece for some pawns, but 20. ... hxg6 just loses a rook.
I'm trying to learn the Sicillian a little, but I'm using too much improvisation
Here's my latest attempt, in which I managed to lose way too many pawns. Any comments would be appreciated.
At any rate, I realize that my opening skills are quite poor, but I would also like some comments on the end game, if there's anything you have to say. Go ahead and skip to move 29 or so if you want to see how I did...
Thanks a bunch!