If you haven't installed Filezilla, you can download it here- http://filezilla-project.org/

Open Filezilla and go to File > Site Manager.

You will need to know which server hosts your domain.   For this example, we are using the server redwood.greenhostit.com

Enter the following settings:

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Host: redwood.greenhostit.com
Port: (leave blank)
Protocol: FTP - File Transfer Protocol
Encryption: Require explicit FTP over TLS
Logon Type: Normal
User: *your username*
Password: *your password*

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- Click Connect

- Once you hit Connect for the first time the message will appear asking you to accept the server's security certificate for redwood.greenhostit.com. Click OK.

Troubleshooting Tip #1:
- If you are behind a firewall and/or a router you will need to use a Passive mode for FTP to get a stable connection.
You can configure this setting as shown bellow:
1.  Open FileZilla and go to Edit -> Settings.
2.  In the Connections section, click FTP and set the Passive mode option.

Troubleshooting Tip #2:
- Under the Filezilla "Advanced Tab", check to see if you have "Server Type" stated as "DOS".  If so, change to Default (Autodetect).