Hi, CuriousKitten!
Do you mean chatting up or chatting with? I suppose the former, which means that there's some flirting going on. Which means the (slight? not-so-slight?) chance of romantic entanglement. In your case (shyness about asking), there are 3 important factors that you need to be aware of:
a) True polyamory requires openness and good communication. In theory, if your friend is truly poly, he should be delighted to explain any points and share his views on poly with you. Don't be shy or embarrassed that you don't know very much on the subject. Who does (outside the poly scene)?
b) Good communication means that - if you do take a step into poly with him - you're going to have to get used to sharing your feelings with him. This includes doubts and fears.
c) Polyamory is not the same to any 2 people. So anything you learn on this site might not apply to your friend... and what you learn from him might possibly be a distortion of true polyamory. (For example - and I'm not for a second accusing your friend of this - some unscrupulous people tell people that they want to screw: "Oh, I'm poly! It's all OK!" when what they're really doing is cheating on their spouses/partners. Polyamory requires consent all 'round.) After that negative blueness, this point continues... and what your friend means by poly and what you read from others on this forum might not be your poly (if you choose to embrace it). With the exception of a few basic ground-rules (respect for others, acceptance of The Other's right to make their own choices, the fact that nobody belongs to anybody else, consent all 'round...) everybody sort of makes it up for themselves as they go along. Though, as you'll see, we swap advice and opinions (as well as stories) like crazy. More than swingers swap wives/husbands! No, swinging isn't poly.
So, enjoy the site, get what you can out of it, give it what you wish to give...
And welcome!
p.s. If you meant chatting with, he might be just as pleased to explain it all (from his point of view.)