You need to download and install "Tunnelblick" first; it's available from http://code.google.com/p/tunnelblick/http://www.tunnelblick.net/. "Tunnelblick" is a bundle consisting of OpenVPN and a simple, nice and easy to use GUI. Just download as instructed there on the web page, but do not run it yet.

Now start the Your Freedom client. Check out the Ports panel, you need to enable OpenVPN there as shown in the picture below:

Now start the Your Freedom connection. Go to the status panel and click on "Connect". After a while, you should see a fully open door as in the picture below:

Contrary to Windows and Linux, this does not indicate that your OpenVPN connection is already up and running; it only indicates that you may start it now. This is the moment where you need to start "Tunnelblick"; if it is already running (you see a black tunnel like icon in the top right corner of the screen), quit it first (right-click on the icon, then choose "quit"). The first time you start "Tunnelblick" it will come up with this window:

Just click "Continue". It will create a dummy configuration file and show it in an editor window as shown below:

Just close the window, we don't need this sample configuration (and you may safely delete the file, it's in Library/openvpn, but maybe you want to keep it for reference). Now that "Tunnelblick" is running, right-click on the "Tunnelblick" icon in the top right corner of the screen:

Choose Connect "Your Freedom". You will be prompted for your password because running OpenVPN is a security relevant operation:

Once you've entered you password (the password you use for your Mac account, not Your Freedom) the OpenVPN connection becomes active within seconds and your applications can freely access the Internet. You'll know the connection is ready when the "Tunnelblick" icon looks like this: