Blundering

I can't win at all. I make careless mistakes too much.

My 163rd KGS game (vs [6k], komi: 0.5, W) 

I overlooked the atari of the triangle, when the opponent throw in 1.

All moves are here.

My 165th KGS game (vs [4k], komi: 0.5, B) 

I overlooked the falling dominoes of the triangle.

All moves are here.

My 167th KGS game (vs [1k], 6 stones game, B) 

I realized the falling dominoes of the triangle, when I played at 2.

All moves are here.

My 168th KGS game (vs [6k], komi: 6.5, B)

I played at 2 without thought.

All moves are here.

I think the cause is the lack of experience.
I must play games instead of reading books!!