I have analysed your game below, commenting on almost every move you made. I hope you find it useful. Looking through games like this and analysing what you did is a really great way to improve. So I encourage you to do this with more of your games.
After the game I will make some key remarks you need to look at to improve.
Based on this I can detect three specific things you can do.
1. Make sure you are comfortable with opening principles (moving pawns before pieces, moving one piece only once, for example). It didn't cost you here. But moving d6 and d5 on your second and third moves was easily avoidable. A better player than white would have punished you badly for that.
2. Before you commit to each move check (a) whether you could have taken any opponent piece, (b) whether any of your pieces are under threat and (c) whether you have a check. Doing this would have enabled you to see 9. ... Qa5+ and would have helped you see that you knight on e7 was en prise for so long).
3. Understand that - certainly once the queens are off the board - a quick mate is unlikely. You need to think about how you can win. Around move 27 you were winning. At that point seek to simplify (exchanges help the player who is up in material in most cases) and think about how to get a pawn to queen. You should have focussed your attention on white's a2 pawn and then look to push your two queenside pawns. This would have put white under intolerable pressure and you would have won more material still. Instead you played 27. ... Bxf2 and didn't even notice that white could take your rook.
I hope you find this useful. As other people have said, everyone was at level 800 at some stage. Most importantly enjoy playing!!!
OP, you, like many others, are at the beginning stages of becoming a good chess player. People call it "wading through the mud," but I don't believe chess is the only discipline where one has to "wade through the mud." Just like any discipline, right now, you suck at it. Michael Jordan wasn't born a good basketball player. He had to acquire the skills after long hours of practice daily. Also, he failed a lot. That's the thing about success. You haven't succeeded until you have failed many many times.
It's normal to start out doing something new and failing all the time. That's the process of learning. You can't get "good" until you've practiced "x" amount of hours. It's especially normal for chess. I saw your game and I can already tell you are a typical 800 player who misses tactics almost all the time and so does your opponent, and the reason why you lost is that you blundered a little more than your opponent. Even at my level, games are usually decided by blunders, however, our blunders are less frequent and sometimes more convoluted to the point where it is a lot harder to see the blunder, but, after it has happened, you can see the position, and easily capitalize on it, if you are the winning side.
You are like the 50 millionthed person who has asked this same question though. I don't know why beginners always ask the same questions over and over again, but anyway, at least you know now so you don't have to worry. It's normal to suck at something when you first start doing it.... Yeah I know it's not as simple as that you've probably been playing for a year or so or whatever and havn't improved yada yada yada. Truth is we don't know how long you've been playing because you didn't give us that information. All you did was tell us you suck, showed one of your games, and expect us to be clairvoyant or something and ask us to tell you something only you can know the answer to, after asking the right questions. This is the wrong question. I hope you don't mind my curtness, but we get people like you that ask this same question over and over again and after they ask the question we never hear from them ever again. I think you will fall into this category. It's not productive to focus on a general idea like, "Why do I suck at chess?" It's better to ask specific questions on how to improve in chess, like, How do I study Tactics?" You may think you know the answer, but the answer you might get here may differ from what you thought was true.
Think before you write.