Learn about the Perfekt tense in German here
The Perfekt tense is the first past tense students need to learn as it's the most common past tense in German. We use it in conversations to discuss events that happened recently. To form the tense, we use an auxiliary verb and a participle.
We normally use "haben" as our auxiliary verb, unless the main verb implies a change of location or change of condition. If it does, we use "sein".
e.g. verbs like "fahren", "gehen", "fliegen" would take sein as their auxiliary, while verbs such as "machen", "geben", "arbeiten" would take haben.
As far as your main verb is concerned, we need to distinguish between regular, irregular, separable, and non-separable verbs. Here is how we form their participles:
When I cover this topic with students, I first do exercises with them practising the haben-sein distinction and then turn to exercises on both auxiliaries and participles so that they pick up the Perfekt form of the most common 60 verbs in German. From there on, it usually becomes fairly intuitive. So give this a lot of practice!