When you write about something that is no longer going on, then you generally write using the past tense and say something like, "In my sophomore year in university, I studied quantum mechanics. The course was very difficult, so I needed a tutor, but I finally understood the basic principles and scored 95% on the final examination".
You cannot say that you learned a course in my college: it's not native-speaker English, not idiomatic, and not semantically accurate. You may learn a language, but you study subjects like math, economics, physics, history.
Be careful about what you say and how you say it. You should probably ask a knowledgeable and commonsensical friend to edit your personal statement.