Hello Sb. / Hello John, Regards.

Hello,

Context: when I go to a chat room and a native English speaker type in the room: “[color=blue]Hello Sb”
I usually answer him/her: “[color=blue]Hello Jack, regards.” Is it ok if I used the word “regards” in that context? Natural?
What bout the punctuation.

Thank you

‘Regards’ is not usually used in that context, particularly upon entering a chat room. It is usually seen as a concluding statement.

Perhaps one of these more natural options would be suitable:
Hello Jack, how are things?
Hello Jack, thanks for the welcome.
Hello Jack, hope you are well.
Hello Jack, how’s tricks? (An informal way of saying ‘how are things?’)
Hello Jack, what’s new? (An informal way of saying ‘what’s happening?’)
Hello Jack.

Many thanks.

Can I use “fine” instead of “well”?

yes

Thank you.