Practice mate, fab game, I’ve played since I was a kid and still play now on a phone app with a mate. You can read up on defence strategy but I think if you keep practicing you’ll get better. Take your time and look ahead as far as you can.
Don't ignore learning about castling, pawn promotion and the move called en passant. These are crucial to developing your game. If you are not confident about the moves then you won't learn.
Picture the chess board as a battlefield with both sides separated by a river. The central spaces are the bridge over that river and so are usually critical to control of the battle. learn to attack and control these squares.
A good game style for novice players, especially if you are playing computers, is the Ruy Lopez, which is all about this style of play. Most computer games I've come across tend to concentrate on this style of attack at the lower levels. This goes way back to the 1490's so you can see how. It centres around the control of the middle squares and will teach you how to support your pieces whilst also attacking the opponents.
Enjoy the game and don't worry about the defeats until you start to get the hang of using your pieces to do a couple of things at the same time.
If, during a game you suddenly get that 'oh shit' feeling then don't be afraid to go back a few moves and replay using fresh moves. At this stage it is all about learning so, although technically cheating, it is more important that you learn than stroking the computer's feelings! Seriously, learning is why they put that feature in the program. If you finally get beaten and don't know where you went wrong then you can look back through your game and try to see how you lost, but don't feel pressured into doing this all the time. You need to enjoy playing chess to want to keep on playing chess!
I used to play a lot of competitive chess as a teenager and got to the semi-finals in the Under 16 County Durham competition but like any sport or activity you eventually get to a level where everyone is better than you and you really need to start putting in some serious training. I tried getting onto my University team but everyone was at least a county champion and some were already internationals. After that I only played socially and eventually lost interest.
A few years ago my 8 year old niece challenged me to a game. She had only been playing a few months and I wasn't really paying attention until I noticed she was beating me and had to fight back to win. I couldn't be beaten by an 8 year old girl.
I recently finished the excellent Queen's Gambit (you don't need to understand chess to enjoy it but it helps) and that has resparked my interest so I'm slowly working my way up the levels on a chess website. The fascination with chess is that the basic moves are fairly easy to understand but the potential combinations are endless.
There's a bloke lives down the road from me who's chairman of the English Chess Federation. He must be a decent player cos he was in the Echo for winning some big tournament (or Congress as I think they're called) up Alnwick a couple of years ago for the second time in 3 years. Teacher at Redhouse school iirc.