Seeking Help with French Grammar: The Use of Subjunctive Mood

 I'm currently learning French and I've come across a challenge that I hope someone can help me with. I’m trying to understand the difference between the passé composé and the imparfait tenses. Specifically, I would like to know when it's appropriate to use each tense in storytelling. For example, if I want to describe a past event, how do I decide whether to use passé composé to indicate a completed action or imparfait for ongoing actions or background description?

Any examples or explanations would be greatly appreciated!