When do I use "sein" and when do I use "haben" in the past tense
"Sein" means literally "to be". "Haben" means "to have". When using the past tense, where there is motion you use "sein" with the appropriate pronoun and the corresponding conjugation. For example, I went to the cinema uses "sein" because there is motion - travelling to the cinema. Therefore you would say "Ich bin ins Kino gegangen". Where there is no motion, one should use haben. For example, I ate an apple is "ich habe ein Apfel gegessen"
SR