Explain the usage of the passé compose vs the imperfect tense

Simply, the passé-composé is used to describe a completed event in the past e.g. J'ai fait mes devoirs (I did my homework); whereas imperfect tense is used to describe an event or action that was ongoing in the past - equivalent to the English 'used to' or 'was doing'. Je jouais dans le jardin chaque jour (I used to play in the garden every day)The passé-composé also refers to to specific actions or time periods in the past e.g. Je suis arrive à l'école à dix heures (I arrived at school at ten o'clock) . The imperfect is used with unspecified time periods e.g. Normalement il mangeais les plats vegetariens (Normally, he ate vegetarian dishes) N.B. The imperfect doesnt always translate as an imperfect in EnglishThe imperfect is also used when describing something in the past e.g. Le placard était grand (The cupboard was big).