Knowledgebase

To log in via FTP (assumming you've alreadying downloaded your FTP program of choice) you can use your cPanel credentials. 

Username would be your cPanel username
Password would be your cPanel password
Host would be your domain name

And we use the default FTP port, 21.

You can also create more restrictive FTP accounts from within cPanel. Simply go to cPanel > FTP Accounts and create new username/password and either create a new directory or choose the directory that the new user will have access to. For these accounts, you will log in with username@yourdomain.com instead. These accounts are helpful in that if someone needs FTP access to your files, like a designer, you don't have to share your cPanel credentials which would give them access to your entire cPanel account. You could create a separate FTP account for them and either give them access to your entire public_html folder, or just your wp-content/themes folder which contains theme files.