You can link your account to our Help Center by logging in to your EVE Online account and authorizing the login by following a link sent to the email address associated with the account.
If you are linking multiple accounts associated to the same email address, you will have to authorize the link by logging in to your other accounts. You will receive an email specifying the name of the account(s) you can login to authorize the link.
If you are having issues logging in to your account or authorizing the link, you can send an email to support@eveonline.com and one of our Game Masters will assist you with this.