6: B just made an armpit/shoulder hit, a type of contact move. W usually wants to stretch out to take advantage of being one move ahead locally.

10: I would pincer. I like the fact that the pincer is also an extension from r8 (which makes it more complicated for B to attack the pincer, I think). (I think I've heard that q14 isn't really good for W in this situation, but it's probably not suboptimal enough to make a difference.)

12: There are two stones in contact: so hane.

20: Solid connection: B could cut and atari immediately!

36: For this move to work, you need to first play s14, then play s16 (an atari), then this threatens to cut.

40: S12 is atari.

52: This was a contact move: don't jump away and leave your stone vulnerable.

Skipping ahead a bit...

96: Great example of a pointless move. Most of the time most of your stones are strategically or tactically vital, so when one gets ataried, you save it without thinking. Here, capturing the stone is almost worthless (seriously - why would it matter if he captured it? It's a two-point gote), so you would rather surround o8 or double approach d4.

98: Wrong direction, imho. (1) You want to attack from your weaker stones to drive him towards/along your stronger stones, where he'll be more vulnerable. (2) You want to attack in a way such that your attacking stones build up power around a valuable part of the board... like the bottom.

104: Great, this is a decent move - build up your power down here, get power at a distance to harass m8. (You could also do it the other way - play some moves threatening m8, then wheel about to attack p4. Just remember that contact moves strengthen the group you are attacking, distant moves weaken it.)

106: Ack, strengthening him for no profit

116: Too small: doesn't threaten the corner, just 10 points in gote.

128: Just play h9, and he's cut off. Huge victory.

Good game. My main suggestion: think move about contact moves. The only reason that playing first anywhere is an advantage is that when the enemy comes close, you are one move ahead. If he touches your stone and you jump away, you throw away your local advantage. Sometimes this is good (for example, when his surrounding position is so strong that you don't have a local advantage anyway), but more often you want to stay one move ahead by playing locally.