Add buff to interaction

Hello. I really don´t know, where can I find help. I will try it here. I want create buff and add it to interaction. I want, that if sim is washing hands, get buff "Clean hands", example. I create buff in Mod constructor (name, description, icon, mood, time). And what now? I tryed find wash hands interaction. I find it in S4 Studio. And what now? I don´t know, how can I continue. I have created buff and finded interaction by Studio. I try copy interaction tuning to opened buff in Studio, but doesn´t work. How to combine interaction + buff to work? I don´t understand it. Can you help me? Or some tutorial, "How add Buffs to interactions"? Thanks for help.