How to communicate with a specific forum "friend" member

I asked a member if there was a way in the future, if I do not get an answer to a post, or do not understand answers that I rcd , if I could contact that person. Their answers were really helpful to me. That person sent me a friend request ,which I accepted.

Now I do not see how do I now communicate with that friend?
Do I put their name in a post to have that person be notified by email?
I searched "friend" and do not find any posts....

Thanks for assistance on this !

Magster