Your first big mistake is at move 58.
This fight is really good for you. What you need to do is keep attacking all four black stones together, not cut them and capture just two.
In the game you tried to cut:
But it would have been better to keep attacking:
Your second big mistake is at move 76. The AI analysis provided by OGS already made that clear, with a big jigsaw pattern in the winrate curve.
Here, Black is threatening to go out at R2 then cut at O3. Locally, you should protect by capturing at R2 or by connecting at O3. You cannot go up at N4. The AI also suggests to tenuki and finish the previous attack by saving the cutstone at H9:
You made a small tactical mistake at move 86. If you simply block, then you have one cut-point:
But in the game, instead of blocking immediately, you took one step back before blocking, and now you have two cutpoints instead of one, which makes it easier for Black to exploit your weaknesses:
At move 98, you played a tenuki, trying to build a small territory in the center. But the fight is not over! In fact it looks like you can kill black right away:
At move 112 you started playing moves inside black territory. This didn’t work and cost you a few points. I suppose that’s the question you’re asking: how to exploit the aji in that region. Well I have to say, I see no aji. Your dead stones is dead and that’s it. You should not play inside black’s territory here.
Compare the result you got by playing inside black territory, with the result you would have gotten if you had played at the borders of white and black’s territories:
At move 196 you wasted a move connecting at Q18. But that is not necessary: your territory on the left of the cut is so solid, Black cannot do anything here. If Black cuts at Q18, then you can capture the cutstone with R18, and if Black cuts at O18, then you can connect at Q18:
At move H5 you played at H5, but this moves is worth zero point because it’s a fake eye, so not really a point of territory. Try to avoid making zero-point moves when there are still moves worth a few points on the board.