FileZilla is used to access your server's files, it has no upload limit, making it a necessity for server owners.
1) Download Filezilla Client from here. Do not download Filezilla Server.
2) Go to the "Files -> FTP File Access" portion of your panel, and after opening Filezilla, hit the leftmost icon to save your server info for future use.
3) Click New Site and begin entering in the information.
4) Hit Connect and you're done! You can access your server in the future from the dropdown menu below Site Manager.