Here is the corrected version with the simple past and past continuous tenses:
When I was a university student about two years ago, I enrolled in a scuba diving course. My scuba diving teacher had a big surprise: I didn't know how to swim. In fact, I had a big fear of water. When I was a child, my parents tried to help me, so they made me take many swimming lessons. Although I tried hard, I didn't learn to swim. When I enrolled in the scuba diving course, I was still afraid of water. Everyday when I entered the swimming pool, I was battling my fear. Fortunately, my courage won every time. Finally, one day while I was practicing my dive