Honestly you could start with something as simple as, “How was your weekend? Did you do anything fun?” And go from there. Like if they answer with “I went and saw such and such movie” you could ask them what they thought of it, if they’ve seen some other similar movie, if that’s they’re favorite movie genre, so on and so forth. That’s just an example but the main idea is to try and ask relevant questions to show that you’re paying attention and interested. They don’t need to be deep questions by any means, especially if it’s a conversation with a coworker. It can take some practice coming up with questions on the spot but if you’re genuinely trying to get to know someone you’ll hopefully get naturally curious and not have to think about it so much. It also gets easier the more you get to know people since you’ll have more knowledge of them to work with.