In cPanel you can use your cPanel username and password for your FTP credentials. These will get you straight to your home directory (pre public_html).
Note that if you change your cpanel password then your FTP password will also change.
You can also set up separate FTP accounts though there is usually no need for this. You can do this under 'FTP Accounts' in the control panel.
In most cases, using the default cPanel username and password will work fine. The hostname is just your domain name, or the IP address that shows on the left hand side of cPanel under 'Shared IP Address'