To get someone's attention in a post, like what you just wrote, add this symbol "@" as the first letter of the screen name, like this
@Dennis S
You can do that to me any time for a specific question, in any article, something like this
@Skittlebisquit how do I send a private message?
@tree is a site moderator, she is really nice.
I'm not sure if my process is same as you.
@Dennis S runs Win 10 with a Chrome Browser, is that right?
You cant break the site or the computer by experimenting. So to send a private message, you click on a person's picture, then click on "start a conversation" then you use thier user name and a subject and then the message, its alot like email.
Or you can just ask someone else to pm you and respond, that might be easier for you, at first