Telling a story in Präteritum
Written narratives often use Präteritum. Strong verbs change their stem: gehen → ging, finden → fand, lesen → las. Ich and er/sie/es usually share the same form; plural wir/sie add -en to the past stem.
Understand the idea
Written stories and reports often use Präteritum to carry the main sequence of events. Strong verbs have an irregular past stem, while regular verbs follow a -te pattern. The choice of tense is also connected to style and region, so it is not simply written equals past and spoken equals perfect.
Build it step by step
Learn the three principal forms together: infinitive, simple past and participle. The past stem normally serves all persons, with the appropriate endings. Ich and er/sie/es usually have no extra ending on a strong past stem. Wir and sie plural add -en; du and ihr may need a linking e after certain stems.
See it in a sentence
Gestern schrieb er einen Brief.
Sie fand den Schlüssel im Garten.
A useful memory aid
Retell a very short story with three verbs, then change its subject from one person to several people. Keep the past stems visible.
A common trap
Do not copy a present-tense vowel change into Präteritum. A verb such as lesen has different present, past and participle patterns that must be learned.