If I have set up email for you, you manage your email account very easily through your cPanel or directly via https://yourdomain.com/webmail. Your email will be your username, your password will be in the ‘Welcome’ email I sent you.
Here’s a video on using your email account on the web:
Manage your email in cPanel
In the case of going throught the cPanel, you simply need to go to >cPanel >Email tab > Email accounts:
Once you are in, you can click on ‘Access Webmail’
You can create new email accounts through cPanel as well on the ‘Add Email Account’ tab.
To view more articles regarding your domain email, creating/sychronizing, etc. HERE.