First login to your Cpanel account.
You can access your Cpanel service by going to https://launchpad.rocketinternet.com then login to your account.
In the navbar select products -> My services. Then select your CPanel hosting service. On the left-hand side, you should see login to Cpanel.
Once logged into Cpanel, scroll to the bottom and you should see the WordPress Manager.
Select New Site.
Make sure the domain in the box is the domain you want to install the WordPress site for. Then select Install. Save your username and password and then log in. Your WordPress site is now set up.