Welcome to the boards, wiztech!
To let him know that you like a thing he does or that you do together, the short answer is: tell him
At the time, you can say "I like that"; if you want to tell him you liked what you both did yesterday, you can say something like "so, yesterday, I liked it when you put your hand on my ass".
To find out how he might like to be touched, your very best plan - and everyone's best plan with a new partner - is to ask. You can find out what he might like to try, and then you can see if those are also things you'd like to do. Equally, you can let him know some things you like or that you might want to try, and ask him if he wants to do those things with you. It sounds like you're both already really comfortable talking about your own sexual lives together, which is great, because it gives you a really good foundation for talking about the shared sexual life you might have. How about talking together in the same kind of way you already have?
Also, there's no one way that you're supposed to react. If you're having fun, if you're comfortable and enjoying what you're both doing, that'll probably show very clearly to him in similar ways to how it does when you're having fun together doing other things.