If you have the option of creating e-mail addresses for the domain name you have registered (either because the registrar offers this as part of the registration price, or because you have taken it out as a separate service), you will be able to manage the e-mail addresses of your domain name via your registrar’s website.
To do this, you will have to sign into your user account on the registrar’s website. You will see the option to create an e-mail account in the e-mail address management section. You will be able to manage the e-mail address by using the webmail tool (the website used to look at the e-mail) offered by the registrar. If you prefer to manage all your e-mail accounts from the same location, you can use the .EUS address that figures in the services you have taken out to manage all your other accounts (Gmail, Outlook, Thunderbird, etc.). When you ask your registrar, they will explain the steps for each service together with the setting-up information that has to be used. Otherwise, you can find the general steps for setting up Gmail in the help article How can I set up my e-mail address in Gmail?