It seems that your topic is narrative.

Beginning: Lessons are a good thing, which makes people increase their wisdom and gain experience in life. I have learned many lessons in my life, but I will never forget one of them.

Then start to continue the reason, process and result of your class.

Conclusion: This lesson made me realize "what what" (I don't know what class you studied here) and understand (know, know, be clear, etc.). It is like a street lamp on the road of life, which dispels the darkness for me and guides the way forward.

PS: I'll go! I haven't written a composition for a long time, but it's still a narrative. Really a little rusty! I miss writing so much, haha ~