First, locate the program file that you downloaded at the time of your purchase and copy it onto the new PC. If you have not saved the downloaded program file, then email to email@example.com and request for a new link to download.
Next install the program in the new PC. Follow the activation procedure as instructed by the program, the same way as if you are activating for the first time. Do not use any previous system id or license id that you may or may not remember.
If you have any question on the activation procedure, refer to http://cavsusa.com/kb//kb/index.php?action=artikel&cat=7&id=203&artlang=en