Download FTP client software like Filezilla. Install it.
FILEZILLA
Click on File >> Site Manager
Click on New Site option
Supply the following details
Host : ftp.domainname ( or ) ip
port : 21
server type : FTPES - FTP over explicit TLS/ SSL
[ Note: If you are using latest version of fiezilla,
Protocol: FTP-File Transfer Protocol
Encryption: Require explicit FTP over TLS.]
Logon Type : Normal
User : your ftp user name
password : your ftp password
Click on connect
Now you should be able to view the local system in left side and server in the right side.
You can now start uploading the contents in your public_html directory by drag the contents from the local system in left side to server in the right side.