You would just log into your account manager. Then click the domain you want the code for. Make sure it's unlocked first and has your WHOIS details. If you have our details or privacy on, it may not work. Once your details are added for at least 4 hours, you can request the EPP code from there. It will be emailed to you right away.
In most cases, the email with the EPP code will come when privacy is on.