In order to use Trubiquity, you first must set up an account. Instructions to do that can be found here:
The first thing you'll need to do is make sure you have the most current version of Java by going to System Preferences>Java and select Update. Here you can find out if you have the latest version, and if not, there should be a button to update.
Once you are signed up and you log in at https://my.trubiquity.net (using Safari, it will not work in Chrome), you will be prompted to run a Java script. You should choose Trust from the pop up window that appears. Once the Java applet is installed, you can proceed with changing the Java settings in two locations on your machine so that Trubiquity will work.
The first place you need to go is System Preferences>Java and select the Security tab. You will see a button towards the bottom that says Edit Site List. Click this button, then click Add, and add https://my.trubiquity.net to the list, then click Ok.
Next, click on Safari in your dock, and go to Safari>Preferences and click the Security tab. Then go to Manage Website Settings. On the menu bar to the left, navigate down to Java. You should see my.trubiquity.net under Configured Websites, with a drop down menu to the right. Click the drop down menu, and select Run In Unsafe Mode. You will get a warning pop-up, and you should click Trust. Then click Done at the bottom of that window.
After these two security settings have been changed, relaunch Safari, log back in to my.trubiquity.net, and you should now be able to send and receive files via Trubiquity!