You can use Windows Explorer if you're running Windows as an FTP client. It works the same as if you were managing files on your PC's hard drive. Just open up a folder, and in the address bar, type in ftp://yourwebsiteaddress.com and then right click the folder, go to Login As... and enter in your cPanel Username and Password. Once logged in, go to public_html and it should be straightforward from there
I use free FTP packages like; ws_ftp or FileZilla. In ws_ftp I set the profile name to whatever you'd like, the host name/address is; ftp.yourname.domain.com, Host Type; automatic detect, user id as; accountname@accountname.domainname.com then your password. Set the startup to /public_html and you should be set...