Puzzles on chess.com are one of the ways to train tactics online. Training tactics is one of the aspects you should train if you wish to improve. But you should be playing games and analyzing them as well. That is for sure. 
How important are Puzzles?
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Du those Puzzles actually help me to win games? I certainly learned to look at the board differently but I'm not sure, if I should shift my attention towards playing and analyzing more Games.