I won this game against a Begginner and he lost by time. If we had infinite time, who would have won?

is wrong shape -- block at either side (D17 or C16), but not D18.

Note the use of 'sgf' tags

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why is that important?
both need to learn basics josekies first.
at first you dont understand why you play josekies but imitate them..
after while you will feel comfortable and understand josekies.
if you disregard josekies you will never improve.

watching your game hurts my eye

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"The more we think we know about
The greater the unknown"
Words by neil peart, music by geddy lee and alex lifeson

20: Not necessary. Using two moves to capture where one will do is as bad as passing. What do you think Black can do?
42: Why?
62: Having these two cutting points (e16, e14) is a big pain in the neck. Better to just block at D15 in the first place. Yes, that means you might lose B13 (can you see how?) but B13 was too ambitious to begin with.
110: I would probably ignore this and play to protect the H18 cut, which is quite urgent.

On the whole, your opponent was quite poor. He kept playing to surround you in wildly overoptimistic ways, including playing out a non-ladder. He had no chance. However, don't let it go to your head...