You can download Cyberduck here.
Double Click the Cyberduck icon to launch the application. In the Bookmark menu, select New Bookmark.
On the resulting window you will need to populate the fields with your FTP information.
In the Nickname: field, enter a name that will help you remember what site these settings are for.
In the Protocol: drop-down menu make sure that FTP (File Transfer Protocol) is selected.
In the Server: field, type the name of your FTP server as specified in your email "MacHighway: New Account Information."
In the Username: field, type your FTP Username.
In the Path: field, type public_html if you're uploading to your first site, or the appropriate file path if you're uploading to an Addon Domain.
In the Connect Mode: drop-down menu, select Passive.
You can now click the red dot in the upper left to close the window.
You should now see a Cyberduck screen showing your newly created FTP bookmark. Double-click the newly created FTP bookmark to access the server. You will then be asked to enter your FTP password to gain access to the the server.
Once your credentials have been verified by the server, you will be connected to your MacHighway server space. You can then drag and drop items from your hard drive onto the Cyberduck window to upload them to the server.