To get better you just need to see more of the tactics for example:
6. Qh5+ is very good as g6 Nxg6 hxg6 Qxg8 and then you are winning.
37-39. Bc4 pins the rook against the king and wins material.
The reason why the end game took so long was because you were a lot worse and if your oppenent played it better then you would have lost.
Good luck- Keep trying.
The problem is , Why it took soo long ?? I and my friend are rivals, although we are not very good at chess I win often but I am unable to end it fast. I think my openings have no problems, but middle and specially end game is worse. Please advice...I will post more games