How do I teach a 5yo another language?

So basically my parents immigrated here 2 decades ago and since I was born here I picked up the language quite quickly. Now I also have a sister who recently started going to the kindergarten but she doesn't really speak the native language. I regret not having taught her the language before all of this but I want to make a change now. Do yall happen to have any tips? The target language is german if that matters And also thanks in advance!