I won atfreelotto.com,they akedme to give my detailson account and cvv but I don't know how to get my prize.

Scam!!

Why would they need your visa?

Did they email you by name or was it "Dear User" or "Dear friend"?

This is a scam. Sadly there are many of them going around and too many people falling prey to them.

Anytime someone wants information, like your name, account number, address, visa, then you have to ask yourself if it's real. I've never received one that's legit and I get at least 5 or more a day.

Delete the email, don't respond and walk away. You don't want to be their next victim.