If I was to guess.

I'm guessing you want them to connect to your homegroup from across the internet. Well, yes you could have them VPN into your network but if you knew how to VPN you would not be asking this question.

Or you may have another question that you didn't write here. As stated it's very unclear what the goal is but in short, it's not a good idea to place a Homegroup on the internet unless you were experimenting and wanted to know how many minutes it took for folk to find and take over that computer.
Bob