There are many cloud options available now a days, such as Dropbox, Google Drive, Skydrive, etc. Each of these options function in a similar way, we will use Dropbox as our example below, feel free to consult with your cloud service provider for specific help with other cloud storage solutions.
The first step is to add the processed hands folder to the cloud's service subdirectory. Just open PT4, go to File > Open User Data Folder, and then share the Processed folder in Dropbox.
You can confirm that this is done correctly by opening Dropbox and ensuring the Processed folder is now available. Please note you will have to do this on both of the computers you intend to syncronise with to ensure each computer is syncing hand histories to your cloud. Some users rename their processed files folders to make it easier to distingush from one another, if you do this please be sure to alter the folder name in PokerTracker as well by changing the Processed Files Folder location found at Configure > Site & Import Options > Preferences.