When you generate the address you get the addy and the private key, so, to get access to the coins you should import the private keys to any wallet. But the problem here is ¿Why you make an address on an online site? that's one of the biggest mistakes you can do because the site can save the keys, or a MITM attack could take the keys when they were created. The right way to make your own paper wallets it's with vanitygen. That's our best option.