If you had those bitcoins before the fork, then you are able to claim them in any wallet that allows you to export your private key and give you those bitcoin gold for free.
Coinomy is an exchange who is giving them for free, just read a little bit more about this wallet/exchange and you will find it out by yourself.
Bittrex has been giving out those coins too, but it is a litle bit more difficult because they are shutting down a lot of accounts without any previous warning about that situation (And you can lose your bitcoins there too)
Yes, I had bitcoins before the fork.
What need doing after export private keys?
Import to Bitcoin gold wallet? (from bitcoingold.org)
