Use was when the subject is singular.
Ex: I was at the park this morning.Use were when the subject is singular you.
Ex: He was ...
Ex: She was ...
Ex: It was ...
Ex: You, Max, were at the park this morning.Use were when the subject is plural.
Ex: We were at the park this morning.Use had as the past tense of have.
Ex: You guys were ...
Ex: They were ...
Ex: I had breakfast today.Use had + past participle to show that one event happened before another event in time.
Ex: You had my phone number but lost it?
Ex: He had a sister.
Ex: She had a job.
Ex: It, the bird, had a nest.
Ex: They had coffee at the restaurant.
Ex: We had tea.
Ex: She had called before I left.
Event 1 (happened first): She had called
Event 2 (happned second): I left
American English Variation
Ex: She called before I left.
Student or Learner