Once you're logged into your client account, in the navy blue menu bar on top, click on "Services" and "My Services". Then below "My Products & Services", click on your active hosting plan. On the next page you will be able to access your cPanel on the left side of your screen where it says "Login to cPanel".
Alternatively you go to https://www.yourdomain.com/cpanel or https://yourIPaddress/cpanel. You can also go to https://yourdomain.com:2083/
If you are experiencing issues logging in via this URL (eg. you are logged out automatically) you can try using: https://cpanel.yourdomain.com .