cPanel is your Web Hosting Control Panel. To login to your cPanel go to: www.yourdomain.com/cpanel
Note: replace yourdomain.com with your actual domain name.
You will then be prompted for your cPanel username and password which can be found in the New Account Information email that was sent to you when you signed up.
Once you've logged into cPanel you'll be able to setup Email Accounts, Upload your website, use the Free Site Builder or install popular software such as WordPress.
You can also use your cPanel username and password to connect to your hosting account using any FTP client.