When discussing events in a work of fiction use present tense. This is called “literary present tense.” A few lines of summary might read like this:
Julie takes her mother to the ballgame and finds their seats are right next to Ron and his family.
In a summary, you would only use past tense if there were a shift in the time frame within the events you’re describing. For example:
Julie refuses to acknowledge Ron. How could the same man that slammed the door on her fingers dote on his children with peanuts and soda?
The verb “slammed” is in the past tense because the event happened before the baseball game.
This literary present tense applies to discussions of the fiction only. When describing your own qualifications or the writing of the story, use past where appropriate:
I received my MFA in fiction from Writing University. My stories have been published in . . .