You need to follow the registration instructions on https://eos.io/instructions » Register » then select your wallet for more details on how to proceed.
Then visit https://eosauthority.com/ to check and verify that you have registered your EOS coins correctly. That's it.
P.S. If you want to securely generate an EOS key pair using the official EOS.IO code, you can follow the method in this video tutorial:
RE: How to Own Your EOS on Launch Day