Finding it hard to get comfortable

I’ve been talking to this guy and we’ve gone on dates and it’s great, he’s super sweet. The thing is I’ve never been in a relationship before (I’m 19) and he likes to hold hands and asked if he could kiss me but I can’t seem to get comfortable with it. Like I want to but I’ve never done anything like that before so I can’t get comfortable with doing anything like that. Any tips on how to loosen up and not be so nervous when he tries to show affection?