What you need to know
In short: the Präteritum is only used when writing novels, articles or reports, while in everyday communication (written or oral) you use the Perfekt. There are only a handful of exceptions from this rule which you have gotten to know in the lessons immediately before this one. Note that although it looks as if the German past tenses are related to the English ones, they aren't. English is way more complex than German in this regard.
This topic is covered in: B1-L10