do I need my best buy membership card to get points.

Reward member? Yes, you do.

i was never given a card, i still get my points

You can have them look up your membership card by your phone number to get points. When you login to BestBuy's website there's a section detailing how many points you have earned. If you have earned enough points for a Reward certificate then depending on the settings for your account the website will automatically issue a $10 or more reward certificate which is good for the amount displayed on the certificate. So, say you have a $10 reward certificate, that means you can get $10 off your total purchase. There might be some exclusions like you can't use the reward certificate to buy a prepaid Visa card but that about it.

You can use your phone number if you don't want to carry the card around. And I don't think they have reward points. Just helps keep track of your purchases.