The past tense is used for events that have already happened.
Alice played her guitar in the school concert last week.
Regular verbs form the past tense by adding -ed (play + ed = played) but there are many irregular verbs that form the past tense in different ways.
Alice went to her guitar lesson yesterday. Her dad took her there by car but she came home on the bus.
Sometimes groups of irregular verbs form their past tenses in the same way.
Things are never that simple, though, and there is usually an odd one out!
The present perfect tense tells us that we have finished something now.
I have eaten my sandwiches.