Dutch has two main past tenses: the perfect (voltooide tijd) formed with hebben or zijn plus a past participle, and the simple past (onvoltooid verleden tijd) formed by adding -te or -de to the verb stem. In everyday spoken Dutch, the perfect is strongly preferred for virtually all past events: Ik heb gisteren gewerkt. Zij zijn naar de markt gegaan. The simple past survives mainly in formal writing, literature and news reporting.
The simple past is formed from the verb stem: werken becomes werkte or werkten, leven becomes leefde or leefden, lopen becomes liep (irregular). The spelling rule for -te vs -de follows the t-kofschip mnemonic: if the stem ends in a letter from the word t-kofschip, add -te; otherwise add -de. Strong verbs have their own stem changes: rijden becomes reed, schrijven becomes schreef, lopen becomes liep. These must be memorised individually.
A practical guide: in conversation and informal writing, use the perfect. In formal essays, journalism and literature, use the simple past for narrative flow. Certain verbs — especially zijn, hebben, worden and the modals — do appear in the simple past even in everyday speech: Hij was moe, Ze had honger, Ik moest werken. Learn those simple past forms first, then expand outward as your level grows.