You need a FTP client software like Filezilla to use FTP. Once you have downloaded and installed a FTP client software follow the below steps.
1. Open the software.
2. Fill in your FTP connection details (host address and login details).
3. Connect to the server.
4. From the folders list, go to public_html folder, this is the folder of your primary domain name.
5. Choose the folder to which you want to upload files.
6. Select files from your system and upload. Once upload is complete, you will be able to view those files in your server.
7. You can also download files from the server to your system in the same way.