First, You will need your Social Booth Key information:
If you do not have this information, please shoot us an email to email@example.com
Please Note: If your license is more than 1 Yr old you will need to pay for the update. The cost is usually $99. However your software will still work just fine, You just won't be able to receive updates for Social Booth
Second, visit Photo Booth Solutions website here: http://www.photoboothsolutions.com/socialbooth/
Download the trial version, Install and enter in your information to get a Trial Version.
Please Note: If you do not want to install the most current version of Social Booth, you can install an older copy here: http://www.photoboothsolutions.com/socialbooth/archive/
You can find the appropriate version by using the date you first got your Photo Booth. Download that version and simply Run the application.
Here is also a link on how to install software on your computer, this procedure is very simple.