Download the zip file containing BusinessMan for the Mac (available here: http://www.businessmancrm.com/download.
When the BusinessMan zip file has downloaded, extract the file to your desktop (or a readily available location), which will create a folder called BusinessMan.
When you have the BusinessMan folder created open the directory and then open the BusinessMan file.
You are now running BusinessMan.
Note: The trial contains sample data. Should you make a purchase of BusinessMan, an empty, ready to use system is available for you to begin managing your business.