Which move was bad and where it could be improved

Obviously i am black metal factor.

[White "carlos0808@chesscube.com"]

[Black "metalfactor@chesscube.com"]

[Result "1-0"]

[WhiteElo "1462"]

[BlackElo "1292"]

[ECO "C47"]

[Time "22:18:41"]

[TimeControl "900"]

1. e4  e5 2. Nf3  Nc6 3. Nc3  Nf6 4. d4  d6 5. dxe5  dxe5 6. Bb5  Qxd1+ 7. Nxd1  Bd6 8. Nc3  O-O 9. Bxc6  bxc6 10. Bg5  Ng4 11. h3  f6 12. Bh4  Nh6 13. O-O-O  a5 14. g4  Be6 15. g5  fxg5 16. Nxg5  Bd7 17. Rdf1  Bc5 18. f3  Be3+ 19. Kb1  Nf5 20. exf5  Bxf5 21. Nd1  Bf4 22. Ne4  h6 23. Be7  Rf7 24. Bc5  a4 25. a3  Rd8 26. Ndc3  Rfd7 27. Nxa4  Ra8 28. Nac3  Be6 29. a4  Bg5 30. Nxg5  hxg5 31. b3  Bc4 32. bxc4  Rdd8 33. Ne4  Rxa4 34. Nc3  Rxc4 35. Ne4  Rb8+ 36. Kc1  Ra8 37. Nxg5  e4 38. fxe4  Rxc5 39. Ne6  Ra1+ 40. Kb2  Rxf1 41. Rxf1  Rb5+ 42. Kc1  g6 43. Nxc7  Re5 44. Rg1  Kh8 45. Rxg6  Rxe4 46. Rxc6  Kg7 47. Ne6+  Kf6 48. Nc5+   1-0

4...d6 is a klunker in the 4 Knights.

Thank you very much appreciated. I shall try to be more careful each move.

True, but quite irrelevant to the outcome of the game, since white played 6.Bb5? and not 6.Qxd8+ or (even better) 5.Bb5! with a typical Steinitz Ruy.

Since he's trying to improve his play and not figure how his opponent could have killed him better, he should have played the main line stuff: Instead of d6, play usually runs 4...exd4 5. Nxd4 Bb4 6. Nxc6 bxc6 7. Bd3 d5 8. exd5 cxd5 9. 0-0 0-0