All stories need some kind of conflict to be interesting (see story structure). There are six main types of conflict.
First you need to know what a protagonist and an antagonist it.
Protagonist: the leading character or one of the major characters in a drama, movie, novel, or other fictional text.
Antagonist: a person who actively opposes or is hostile to someone or something.
Antagonist: a person who actively opposes or is hostile to someone or something.