Do I have to store my Bitcoin in a specific wallet (I might be new, but I'm not stupid enough to send my coin to you ;-) ), or do anything to activate this, or will it happen automatically? (If the fork goes ahead, of course).
You need your coins to be stored in a wallet that you have the private keys to so that once the fork happens, you can use the same private key to gain access to the newly forked Bitcoin gold (or whatever it will be called)
Just make sure not to store your coins in an exchange like Coinbase because you don't have access to the private keys of your wallet and eventually won't be able to claim your Bitcoin gold.