If the narration describes something that specifically happened in the past, it should be in past tense.
"Yesterday, I walked to school."
However, If you want the narration to describe something as it happens to the protagonist, and as they experience it moment by moment, you can use present tense.
"Today, I walk to school."
Both are acceptable was to tell a story, but please take care to stick to the one you choose.
This can be tricky when the narration is a journal or diary entry, but just remember what the character is writing about and when they experienced it. If they describe their schoolday once they arrive home, it should be in past tense.
"Today, I walked to school."
If they discribe the emotions they feel as they write, it should be in present tense.
"I want to walk to school tomorrow."
Please comment if you have anything to add or dispute.